GB1600111A

GB1600111A - Temperature indicating compositions

Info

Publication number: GB1600111A
Application number: GB17321/78A
Authority: GB
Original assignee: Akzo NV
Current assignee: Akzo NV
Priority date: 1977-05-02
Filing date: 1978-05-02
Publication date: 1981-10-14
Also published as: NL186833B; DK189778A; NL7804671A; SE7805010L; FR2401215A1; DE2818833A1; BE866549A; DE2818833C2; AU3565278A; FR2401215B1; ES469337A1; NL186833C; IT7822910A0; IT1096189B; AU523240B2; JPS5415483A; DE2858739C2; BR7802743A; JPS6260435B2

Description

(54) TEMPERATURE INDICATING COMPOSITIONS (71) We, AKZO N.V. a Company organised and existing under the laws of the Kingdom of the Netherlands, of IJssellaan 82, Arnhem, the Netherlands, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to temperature-indicating compositions and to temperature indicating devices containing these compositions and, in particular, to novel stable compositions which change colour sharply upon a transition from a liquid state to a solid state or from a solid state to a liquid state, the change of state being at substantially a predetermined temperature corresponding to a temperature to be measured.

In the temperature, indicating devices which constitute one aspect of the invention various proportions of the organic constituents making up these novel compositions may be placed in a plurality of spaced regions such as a grid, preferably at evenly spaced temperature increments, to determine a like plurality of predetermined temperatures in a given temperature range and thus form a thermometer; when these regions are subjected to a temperature within this temperature range, one or more of the regions containing these compositions will change from a solid state to a liquid state with a corresponding change in colour indicating a temperature within the temperature range to the nearest temperature increment.A novel temperature indicating device is disclosed comprising a heat conducting carrier having one or more cavities, each substantially filled with a novel composition which changes from opaque to transparent upon a corresponding change from solid to liquid on top of an indicator means located at the bottom of the cavity; the temperature indicating device contains a substantially spherical void space between the bottom of the cavity and a transparent cover sheet means in sealing engagemnt with the heat conducting carrier means overlying and above the cavity, which spherical void space acts to magnify the colour change.

The transparent cover sheet and the heat conducting carrier means are preferably bonded to each other by means of a layer of a pressure-sensitive adhesive which consists entirely or substantially of polyisobutylene.

For many years attempts have been made to construct an inexpensive device of mixtures or materials of any kind which would change in some characteristic manner visible to the naked eye at substantially the temperature to be measured, so that the inconveniences of the conventional mercury thermometer could be avoided.

United States Patent Specification No. 3,946,612 discloses the use of a heat conducting carrier having a plurality of spaced cavities with a corresponding plurality of solid solutions each comprising an organic layer of at least two different organic chemicals (orthochloronitrobenzene and ortho-bromonitrobenzene) in varied composition ratios deposited in the cavities, these layers changing from being opaque to clear upon a change in phase from solid to liquid. This organic layer formed a part of a sandwich for an indicator layer between it and a masking or opaque layer. When a cavity was heated to a predetermined temperature, the composition would change from a solid to a liquid state, permeating the indicator forcing a dye into the opaque layer to change the colour of the opaque layer to the colour of the dye.A device of this type with three internal layers in the cavity is hard to manufacture and very expensive. Sometimes the organic composition would not totally change from liquid to solid, so that nucleation sites remained in the organic layer; hence resolidification quickly occurred upon withdrawal of the thermometer, and not all the dye was forced into the upper or opaque layer. Because of the size of the layers, it was sometimes hard to see the change in colour when only some of the due was transferred into the previously opaque layer.

United States Patent Specification No. 3,700,603 discloses pairs of substances that change colour upon change in phases for use in thermometers. However, no suitable solvent system was employed, so that a number of different pairs of substances would be needed for almost any temperature range to be determined.

This also applies to the mixtures of acceptor-donor chemicals disclosed in United States Patent Specification No. 3,576,604, which were used for detecting heat effects by colour changes. The colour changes, however, occurred in the absence of any solvent.

It has now been discovered that certain organic compounds (to be described hereinafter) form novel solid solutions which undergo a change in state from solid to liquid at precise and predetermined temperatures with a corresponding change in colour visible to the naked eye, and likewise, from liquid solutions which undergo a change in state from liquid to solid with a corresponding change in colour visible to the naked eye.

Accordingly the present invention provides - a composition consisting essentially of at least: (1) a solvent comprising of a single substance or a mixture of substances and adapted to change at substantially a predetermined temperature from a solid phase to a liquid phase and (2) an indicator system comprising one or more substances different from the solvent, the indicator system being soluble in the solvent when the latter is in the liquid phase, and reversibly changing its colour as visible to the naked eye when the solvent passes from the solid to the liquid phase and from the liquid to the solid phase.

Although not yet investigated from all the colour changes that have been discovered, we have found on the basis of experimental work that in most cases another requirement for the novel composition is that the solubility of the indicator system in the solvent when the latter is in the solid phase, should be so much lower than the solubility of the indicator in the solvent, when the latter is in the liquid phase, that the indicator is partly or entirely separated when the solvent passes from the liquid to the solid phase.

The term "solid solution" is well known and usually refers to a homogenous solution of one solid in another. The novel solid solutions used in the present invention are composed of two or more, preferably three or four different organic compounds with varying proportions of at least two compounds which form a "solid solution". This solid solution forms a solvent for one or more of the indicator compounds in the liquid state.

Each novel solid solution undergoes a rapid change of state at a precise and predetermined temperature or substantially thereabouts. By a "change in colour visible to the naked eye" of a source we mean a change in the wavelength of luminous flux of light (from the source distributing or reflecting such energy in the region of the Electromagnetic Spectrum from about 3900 Angstrom units to about 7600 Angstrom units before or after the change, (or preferably both) visible to a person of normal vision and eyesight wherein the intensity of the luminous flux surrounding the source is more than or about 5 lumens per square foot (ft-c). In most instances, this change in the wavelength of luminous flux to the eye will be at least 175 Angstroms, and preferably at least about 500 Angstroms.

The novel composition consists essentially of (A) a solvent adapted to change at a predetermined temperature from a solid phase to a liquid phase, and (B) an indicator comprising one or more organic compounds soluble in the solvent in the liquid state and adapted to change the colour of the composition visible to the naked eye upon the change of state of the solvent at substantially the predetermined temperature, which indicator is preferably selected from (1) a group of single compounds which are monoazo, disazo, triaryl--methane, xanthene, sulphonephthalein, acridine, quinoline, azine, oxazine, thiazine, anthraquinone or indigoid compounds and the individual compounds: Aurantia, Orasol orange RLN, Diamin green B, Direct green G, Fast red salt 3 GL, Fast blue salt BB, Fast garnet salt GBC. Carta yellow G 180% Murexide, Savinyl blue GLS, Irgalith blue GLSM, Phthalocyanine and Alcannin, (2) mixtures of (a) one or more organic acid compounds, having a pK of less than four, and (b) one or more dyes or basic indicators.

(3) mixtures of (a) one or more organic acids having a pK of less than 2 and (b) one or more acid dyes or acid indicators, (4) mixtures of (a) one or more organic acid compounds having a pK of less than 4 and (b) one or more of the compounds (1) above, (5) mixtures of (a) one or more basic dyes or basic indicators and (b) one or more of the compounds (1) above, (6) mixtures of (a) one or more dyes having a molecular structure containing a lacetone group, and (b) one or more acids having a pK in the range of from 8 to 12.

The compounds mentioned under (1) above are classified according to the Colour Index, 3rd Edition (1971), published by the Society of Dyers and Colourists, Great Britain and to Conn's Biological Stains (9th ed 1977). Monoazo dyes which are preferred are: 4-(p-Ethoxyphenylazo)-m-phenylene-diamine monohydrochloride, Orasol navy blue, Organol orange, Janus green, Irgalith red P4R, Dimethyl yellow, Fast yellow, Methyl red sodium salt, Alizarin yellow R, Eriochrome black T, Chromotrope 2R, Ponceau 6R, Yellow orange S, Brilliant Ponceau 5R, Chrysoidin G, Eriochrome black A, Benzyl orange, Ponceau G/R/2R and Chromolan yellow.

Disazodyes which are preferred are. Fat red BS, Sudan red B, Bismarck brown G, Fat black, Resorcin brown, Benzofast pink 2 BL and Oil red EGN.

Triarylmethane dyes which are preferred are: Methyl violet, Xylene cyanol FF, Erioglaucine, Fuchsin NB, Fuchsin, Parafuchsin, Aurintricarboxylic acid ammonium salt, Patent blue, Victoria blue R, Crystal violet and Irgalith blue TNC.

Xanthene dyes which are preferred are: Phloxin B, Fluorescein sodium salt, Rhodamine B. Rhodamine B base. Rhodamine 6 G, Pyronin G, Irgalith Magenta TCB, Irgalith pink TYNC. Eosin scarlet, Eosin yellowish, Erythrosin extra bluish, 4'5'-Dibromofluoroescein, Ethyl eosin. Gallein, Phloxine, Erythrosin yellowish blend and Cyanosin B.

The sulphonephthaleins which are preferred are: Cresol red, Chrlorophenol red, Chlorophenol blue, Bromophenol blue, bromocresol purple and chlorocresol green.

The acridine dyes which are preferred are: Coriphosphine O, Acriflavine and Acridine orange.

The quinoline dyes which are preferred are: Pinacyanol chloride, Pinacyanol bromide, Pinacyanol iodide, Quinaldine red, Cryptocyanine, 1,1'-Diethyl 2,2'-cyanine iodide, 2-(p-Dimethylaminostyryl)-1-ethyl-pyridinium iodide, 3,3'-Diethylthiadicarbocyanine iodide, Ethyl red, Dicyanine A, Merocyanine 540 and Neocyanine.

The azine dyes which are preferred are: Neutral red chloride, Neutral red iodide, Nigrosine, Savinyl blue B, Orasol blue BLN, Safranin O, Azocarmin G, Phenosafranine, Azocarmine BX and Rhoduline-violet.

The oxazine dyes which are preferred are: Solophenyl brilliant blue BL, Nile blue A, Gallocyanine, Gallamine blue and Celestine blue.

The thiazine dues which are preferred are: Methylene blue, Thionin, Toluidine blue 0, Methylene green and Azure A/B/C.

The anthraquinone dyes which are preferred are: Savinyl green B, Savinyl blue RS, D+C green 6. Blue VIF Organol, Alizarin, Alizarin cyanin 2R, Celliton blue extra, Alizarin blue S, Nitro fast green GSB, Alizarin red S, Chinalizarin, Oil blue N, Solway purple and Purpurin.

The indigoid dyes which are preferred are: Ciba blue, Indigo synthetic, Cromophtal Bordeaux RS and Thioindigo red.

Most preferable dyes are: pinacyanol iodide, chlorophenol red and alizarin blue S.

It has been noticed that when a small but effective amount (generally a weight fraction from about 0.005 to about 0.2 weight percentum of the entire composition) of one or more of the compounds (1) above or one of the other organic moieties to be described is combined with a suitable solvent, for example, a pure mixture of ortho-chloronitrobenzene and ortho-bromonitrobenzene for use in clinical applications, the temperature of the change of state of a number of solid solutions with a corresponding change in color may be accomplished at approximately l/lO"C intervals, i.e., a change of state of one novel temperature-sensitive composition at a temperature 1/10 C different from the temperature of change in state of another novel composition in an adjacent region contaning another proportion of the same organic moieties in ortho-chloronitrobenzene and orthobromonitrobenzene.

Thus, for example, in human clinical applications where temperature measurements in the range of about 35"C to about 42"C particularly from 35.5"C to 40.5"C are usually desired. In the latter case 50 different solid solutions (differing in their percentage compositions but otherwise made from the same two components) will provide all of the necessary temperature gradations at increments of 1/10"C i.e. 35.5 , 35.6 , 35.7 , up and including 40.4"C.

The solution of ortho-chloronitrobenzene and ortho-bromonitrobenzene, when the ortho-bromonitrobenzene varies from 56.2 weight percent to 96.0 weight percent, provides an excellent starting mixture for determination of temperatures in the human clinical temperature range. Usually the addition of the Group I or other organic moieties (hereinafter sometimes "organic moieties") hardly affects the melting temperature of the solid solvent.

It is advisable that the melting point of the organic moieties be above the melting point of the solvent system. When the indicator system consists of a mixture of compounds it is preferred that the melting point of each of the constituents be substantially above the melting point of the solvent system selected, and it is more preferred that these compounds melt at more than 60 degrees above the melting point of the solvent system.

Regardless of the solvent system selected for a given predetermined temperature range, it is necessary that the organic moieties selected for the color change constitute a small but effective amount of moieties, e.g., at least that amount sufficient to provoke a color change visible to the naked dye, and preferably about 00.5 to about 0.2 weight percent of the solvent material.

If too small an amount of organic moieties is employed, the colors and the color change are too faint under weak light; if too large an amount is employed, the colors are too dark and the color change is harder to visualize and there is a possibility that the sharpness of the melting point will be affected. It is also noted that the organic moieties should be substantially free of impurities; generally, such impurities should be kept less than 0.3 percent of the entire compositions.

Instead of one or more compounds (1) above, to be used in the novel composition of matter, mixtures can be employed.

The group of organic compounds with a pK less than about four generally consists of organic acids and/or the halogenated sulphonephthaleins, which are soluble in the selected solvent, when the latter is in the liquid state. Examples of these acids include oxalic acid, maleic acid, dichloroacetic acid, trichloroacetic acid, 2-naphthalenesulphonic acid, chloroanilic acid, bromophenol blue, bromothymol blue, chlorophenol, red, bromochlorophenol blue, bromocresol green, 3, 4, 5, 64etrabromophenolsulphonephthalein, bromophenol red, chlorocresol green, chlorophenol blue, bromocresol purple and 2,4dinitrobenzenesulphonic acid.

The group of basic dyes or basic indicators are generally the amino-triphenyl methanes, also known as the triaryl methanes, or their soluble salts, 8-hydroxyquinoline and the quinoline dyes, preferably the cyanines. Examples are: basic fuchsin, pinacyanol iodide, pinacyanol chloride, pincyanol bromide, 2-p-(dimethylaminostyryl)- 1-ethyl-pyridinium iodide, crystal violet, cryptocyanine, dicyanine A, 3,3 '-diethylthiacarbocyanine iodide, 1,1'-diethyl-2,2'-cyanine iodide, ethyl red, quinaldine red, ethyl violet, brilliant green, pararosaniline, pararosaniline acetate, 8-hydroxy-quinoline, 1-ethylpyridinium iodide and 5-(p-dimethylaminobenzylidine) rhodanine.

Preferably the weight of the acid compounds is about three or more times the weight of the basic compounds. The above mentioned pK values refer to the pK values as measured in water. Generally it is preferred that the pK of the acidic compound is lower than the corresponding pK value of the basic compound. Preferably the acid compounds have a pK value less than about four and the basic compounds have a pK value less than about 5.

It should be noted that when the basic compound consists solely of one or more aminotriphenyl methanes or their soluble salts, the acid compound must be selected from the group consisting of tetrahalogenated sulphonephthaleins and the other organic acids having a pK of less than about 2.

Preferred combinations of acidic compounds having a pK less than about 4 and basic dyes or basic indicators are bromophenol blue/basic fuchsin, chlorophenol blue/ethyl red and trichloroacetic acid/3 ,3 '-diethylthiadicarbocyanine iodide.

Mixtures of one or more organic acids having a pK less than about 2 and one or more acid dyes or acid indicators, used in the novel composition change colour when the solvent passes from the solid into the liquid phase or the reverse. In this combination the acid dyes used are preferably halogenated sulphonephthaleins.

Mixtures of one or more organic dyes, having a molecular structure containing a lactone group and one or more acids having a pK of about 8 to about 12, used in a solvent also change colour when the solvent passes from the solid phase into the liquid phase or the reverse. In that combination the preferred compounds are crystal violet lactone and one or more of acids such as phenol, bisphenol A, pyrocathechol or 3 nitrophenol.

While sometimes under fortuitous circumstances the solvent system may consist of only one compound, in most instances (as those skilled in the art will appreciate) the temperature to be determined will not readily be obtainable without mixing two or more organic compounds for the solvent system. Hence, for a temperature-indicating device, two or more related organic compound constituents in the solvent are especially helpful for measuring forty or more temperatures located at regular increments.

It is apparent from the foregoing description that the selection of one or more inert solvents towards the organic moieties for use in the novel composition requires judicious and careful scrutiny, since not all organic compounds are useful for this purpose and many may fall outside a desired temperature range. A suitable solvent may be any solvent which is inert towards the organic moieties and in which the organic moieties are soluble while the solvent is in the liquid phase.

Thus it has been discovered that aromatic organic compounds, which have analogous chemical structures (e.g., analogs, homologs and optical isomers), have substantially the same molecular volume or have similar crystalline structures (e.g., isomorphous) and which form the novel solid solutions useful for the purpose of this invention, are especially useful for solvent system constituents in preparing a grid of novel compositions to be used in a predetermined temperature range for the determination of a temperature falling within said range. In addition, it is preferable that the solvent solutions have a linear or a substantially linear temperature composition liquidous curve, particularly over the desired temperature range such as, for example, over the human clinical temperature range.

Exemplary aromatic solvents are ortho-chloronitrobenzene, orthobromonitro-benzene, naphthalene, 2-ethoxybenzamide, 1-thymol, 2-naphthol, ortho-iodonitrobenzene, metaiodonitrobenzene, para-iodonitrobenzene, para-chloronitrobenzene, metabromonitrobenzene, para-bromonitrobenzene, para-dibromonitrobenzene and para-toluic acid.

In some instances simple alcohols, other organic substances and even water may be suitable rather than polar, weakly polar or non-polar aromatic compounds. In addition to the aromatic compounds colour changes were observed in aliphatic compounds such as t.butanol, stearic acid, 1-tetradecanol, n-tetracosane, laurylalcohol, formamide and paraffin, and in heterocyclic compounds such as dioxane, symmetric trioxane, indole and dibenzofurane.

It should be emphasized, of course, that a suitable solvent useful for one selection of organic moieties may not be useful for another.

It is well within the range of knowledge of those skilled in the art to find for a given temperature range to be measured and for a color change desired a suitable solvent.

The solid solutions made from a binary mixture of ortho-chloronitrobenzene and ortho-bromonitrobenzene, having a proportion of ortho-chloronitrobenzene to orthobromonitrobenzene of about 43.8 - 56.2 to about 4.0 - 96.0, have been found to be most preferable for use in temperature measurements in the clinical range.

In investigating the compositions of the present invention we have discovered that in many cases the indicator substance or mixture of substances is at least partly separated from the liquid solvent during its solidification. When the solidifying composition is seen by microscopy one observes that the indicator substance is to a large extent excluded from the growing solvent crystals and concentrated in the remaining liquid phase. When the solidification process proceeds, the concentration of the indicator substance increases until the solvent has completely solidified. The indicator substance has then been excluded from the solvent to a large extent. During the increase of the indicator concentration in the liquid part of the solvent or during the actual exclusion of the indicator from the solvent the indicator changes its colour.

On subsequent heating the solvent crystals melt again redissolving the indicator and thus restoring it to its original colour.

An example of an especially preferred compound (1) above is pinacyanol iodide at a concentration of 0.025 per cent by weight. When dissolved in an ortho-chloronitrobenzene/ ortho-bromonitrobenzene (OCNB/OBNB) solvent, the liquid composition is an eyeappealing brilliant blue. During solidification at room temperature of the OBNB/OCNB solvent, the pinacyanol iodide becomes increasingly concentrated in the correspondingly decreasing proportion of liquid. The pinacyanol iodide increases in concetration to the point that when solidification of the composition is complete, the pinacyanol iodide is isolated in small particles around the crystalline structure of the OBNB/OCNB solvent and from the view of an observer turns the color of the entire composition to an attractive rose.

When the solidifying composition is seen by any form of microscopy, the beads of pinacyanol iodide particles appear quickly on the surface of the crystalline solvent in an aggregate.

It was found that upon heating the solidified composition until melting the pinacyanol iodide redissolves immediately, thus restoring the brilliant blue colour.

Why pinacyanol iodide changes its colour upon being separated from the solvent compounds is not fully understood at this time. The colour change may be caused by an intermolecular interaction between the pinacyanol ion and the counter ion. It is most likely that the pinacyanol iodide crystals, being formed upon separation of the solvent, consist of a stack structure with columns of positive dye ions and negative counter ions. Such a structure might give raise to a drastic change in resonance as compared with the unpertubed state of dissolved pinacyanol iodide.

Another example of an especially preferred compound (1) above is chlorophenol red at a concentration of about 0.05 percent by mass. When dissolved in a solvent such as OCNB/OBNB, dibenzofurane, para-toluic acid and other halogen nitrobenzenes, the liquid composition has a yellow colour.

During solidification of the composition the chlorophenol red is concentrated in the remaining liquid part of the solvent. When the solidification has been completed the solid has a nice red colour. Microscopic investigation of the solid composition shows that the chlorophenol red particles have been substantially separated from the solvent crystals. In our opinion the intra-molecular rearrangement of a sultone group, when the chlorophenol red is dissolved in the liquid solvent, into a quinone structure, when the chlorophenol red is separated, is responsible for this colour change.

When the indicator system comprises more than one component the colour change often will be caused by chemical reactions between the indicator compounds.

An example of a preferred mixture of a basic dye and an acid with a pK less than about 4 comprises chlorophenol blue and ethyl red. When these compounds are dissolved into OCNB/OBNB, up to a total concentration of about 0.05%, the mass ratio of chlorophenol blue/ethyl red being 3:1, the liquid phase shows a red colour. When the composition of matter goes from the liquid to the solid state, a remarkable colour change from red to yellow is observed.

In the above mentioned case an acid-base reaction probably occurs. When the composition is in the liquid phase the chlorophenol blue and the ethyl red are in a diluted state and therefor the ethyl red is in its basic red form; hence the liquid shows a red colour.

During solidification of the solvent the indicators are concentrated in the liquid phase and the chlorophenol blue protonates the ethyl red, thus converting the latter into its colourless acid form.

As a result the solidified composition is coloured yellow.

According to the above theory the halogenated sulphonephthaleins are considered to be acids.

Similar reactions will occur when simple organic acids, e.g. sulphonic acids, trichloroacetic acid, and basic dyes are employed.

Since many sulphonephthaleins already change colour when applied as a single compound, this colour change may affect the colour change resulting from the acid-base reaction.

Preferably the compositions of the present invention are substantially free from impurities which might induce immediate resolidification after melting.

Generally the impurities are less than 0.3 weight percent of the entire composition, thus rendering the composition of matter capable of undercooling.

We require that if and only if a given composition reaches one hundred percent liquid after melting, will that liquid remain liquid for more than several seconds when withdrawn from the source whose temperature is to be measured; less than one hundred percent melting will cause the composition to return almost instantaneously to its solid state when the composition is withdrawn from the above-mentioned source. It is only by these means that a commercially useful composition for disposable thermometry can measurably advance the state of the art. We have found, that the best method of obtaining the undercooling property in each of our novel compositions of matter is to render them substantially free of impurities, although doubtlessly the undercooling effect can be made through different mechanisms.For example, several organic solvents exist for the organic moieties (high molecular weight aliphatic alcohols) which become suddenly very viscous in their liquid state close to solidification, so that they possess the undercooling property despite the presence of some impurities. Hence, this limited number of solvents are equivalent to the general solvents used in our invention which are substantially free from impurities.

In some cases it is advantageous when the undercooled liquid composition of matter resolidifies at a predetermined temperature, in order to recrystallize the composition after accidental heating above its melting point, during e.g. storage or shipment.

We have found that an amount of 0.001 to 10.0% by weight of a soluble or a non soluble nucleating agent renders the composition of matter of our invention capable of recrystallization at a substantially predetermined temperature.

Preferred nucleating agents are anthraquinone, talc, aluminium oxide, silicon dioxide, modified silica, boron, titanium carbide, diamond and molybdenium disulfide.

A particularly preferred nucleating agent is talc, having a particle size in the range of from 0.1 to 10 micrometers.

Besides use in disposable oral thermometers, the novel compositions of our invention may be employed for the detection of overheating in engines, for the detection of leaks from steam traps (the indicator may be placed on an uninsulated piece of pipe just below the steam trap), for the detection of high temperatures in the surroundings of computers, home furnaces and appliances, as well as on packages for foods, forehead, skin and rectal temperature indicators.

The invention also provides a temperature-indicating device comprising a heat conducting carrier and a transparent cover sheet means in sealing engagement with the carrier, the carrier having one or more spaced regions defined therein for the determination of a like number of predetermined temperatures in a predetermined temperature range, with a like number of different compositions contained therein, and with a single composition being deposited in each of the regions and being associated with a single one of the predetermined temperatures, the compositions used being the compositions as described in the previous and claimed in the latter part of this specification. Preferably the above-mentioned regions are cavities in the heat-conducting layer.

The compositions used preferably are in an essentially linear melting point-tocomposition relationship over the temperature range represented by the plurality of compositions.

When the cavities are filled up to a level of about 60% of the content of each cavity with compositions being associated with a predetermined melting point and the transparent cover sheet means is put in sealing engagement with the carrier, a preferred device is obtained wherein each of the compositions associated with a particular cavity fills the cavity except for a substantially spherical void within the cavity.

This spherical void acts to magnify the colour change in the cavity.

The compositions being used in the device of this invention consist of the previously mentioned novel compositions including the compositions which contan one or more nucleating agents, in order to render the composition capable of recrystallization at a substantially predetermined temperature.

As an alternative to the nucleating agents mentioned above, the surface of the heat-conducting carrier may be treated by anodizing (anodic oxidation) or chemical passivation to create nucleating sites.

The anodizing procedure may be carried out in e.g. sulphuric acid or phosphoric acid or under other circumstances as will be known to those skilled in the art.

Chemical passivation of the surface may be carried out by an etching procedure in 2% sodium hydroxide. a subsequent treatment with 10% nitric acid and washing with water.

Wherever throughout this specification "weight" is used it has the meaning of "mass".

The invention also relates to a temperature-indicating device of the above described types wherein the transparent cover sheet means and the heat-conducting carrier are sealed to each other by means of an adhesive layer of a pressure-sensitive adhesive which consists entirely or substantially of polyisobutylene.

United States Patent Specification No. 3 002 395 describes temperature indicating devices in which use is made of a low-temperature bonding adhesive, such as an epoxy resin or a pressure-sensitive adhesive substance having a basis of silicones. For various reasons, such as insufficient resistance to the chemicals used, release of low-molecular constituents which detrimentally affect durability, temperature indication and reproducibility, and the fact that they are insufficiently impervious to chemicals, these adhesives have been found to be unsuitable.

It is preferred that the polyisobutylene used as the pressure-sensitive adhesive should have an average molecular weight in the range of from 50,000 to 5,000,000, more particularly 150,000 to 4,000,000.

A very favourable combination of adhesive strength and resistance to the chemicals present in the cavities is obtained if the adhesive layer consists of a mixture of 30-70% by weight of polyisobutylene having an average molecular weight of 70,000 to 100,000 and 70-30% by weight of polyisobutylene having an average molecular weight of 1,000,000 to 3.500,000. It is preferred that said mixture should consist of practically equal parts by weight of the respective constituents. The adhesion between carrier layer and pressuresensitive adhesive can still be further improved in various ways. Such improvement is obtained if the carrier layer consists of aluminium foil having an etched surface.

Improvement of the adhesive strength can also be realized by making making use of a carrier layer of aluminium foil coated with a polyisobutylene surface layer applied from a solution in an organic solvent.

An example of a suitable solvent is hexane.

It is preferred that such a surface layer should have a thickness of 2 to 10 micrometers. It is preferred that the polyisobutylene used for such a surface layer should have an average molecular weight in the range of 2,000,000 to 3,500,000. The use of a carrier layer having a surface thus modified makes it possible to obtain good adhesion also when employing polyisobutylene having a relatively high molecular weight. A carrier layer coated with a surface layer of polyisobutylene is therefore preferably used if the carrier layer is bonded to the transparent cover layer by means of a pressure-sensitive adhesive layer of polyisobutylene having an average molecular weight in the range of 2,000,000 to 3,500,000.

The pressure-sensitive adhesive to be used according to the invention can be applied as thin layer to one side of the film material used as transparent cover layer, for instance polyester film. This may be done from a solution in, for instance, hexane or from the melt.

The thickness of the adhesive layer thus formed is as a rule 10-100 micrometers, and preferably 20-60 micrometers.

The polyisobutylene-coated side of the transparent cover layer is brought into contact with the carrier layer on the side where the cavities to be closed off are positioned, and bonded to it under pressure without the temperature being increased.

The bonding pressure applied is generally in the range of 1 to 50 kg/cm2.

Various types of polyisobutylene are suitable to be used for this purpose. It is preferred that the average molecular weight of the polyisobutylene should be in the range of 50,000 to 5,000,000. By average molecular weight is to be understood the viscosity average molecular weight. This is calculated from the intrinsic viscosity, which in its turn is determined from the rate of flow of a solution having a concentration of 1 g/dl in isooctane through the capillary of an Ubbelohde viscometer at a temperature of 20"C.

For the calculation of the following formula is used: [n] = tD n/Co 3l = = 3.06 x 10-4 x Mv 0.65 where: [n] = intrinsic viscosity = = t/to - 1 = specific viscosity t = rate of flow of the solution, corrected in accordance with Hagenbach - Couette to = rate of flow of the solvent, corrected in accordance with Hagenbach - Couette c = concentration of the solution in g/dl Mv = average molecular weight The polyisobutylene used has a good resistance to the chemical substances present in the cavities, does not influence their melting point, and hardly absorbs chemical substances and does not allow the passage thereof.

The invention will be further described with reference to the accompanying drawings.

Figure 1 is a partial overhead plan view of a thermometer over part of the human clinical range of temperatures embodying the principles of this invention in degrees Celsius; Figure 2 is a partial overhead plan view of a thermometer over the human clinical temperature range embodying the principles of this invention when in degrees Fahrenheit; Figure 3 is a view of a thermometer with 100F increments when using the novel compositions of matter of this invention in a commercial application; Figure 4 is a plan view of a temperature-indicating device from the horizontal (together with a plan view from the vertical of a label on said device) using the novel compositions of matter of this invention for indication of a temperature exceeding a predetermined safe limit.

Figure 5 is a cut-away three dimensional view from a skewed angle of a thermometer comprising a heat-conducting carrier means with a grid of cavities thereon, enclosed in a case so that only a handle of the heat-conducting carrier means protrudes; Figure 6 is another three-dimensional view from the same skewed angle as Figure 5 of the thermometer when removed from the case of Figure 5, except that it reveals a clinical temperature scale from 96.0 F to 104.8"F in the form of a grid of cavities in the heat-conducting carrier means; Figure 7 is a partial plan horizontal view taken along line 11-11 in Figure 6, revealing several cavities in the heat-conducting carrier means, each surrounded by a transparent cover sheet means and a bottom transparent bottom plate means; ; Figure 8 is a plan view of a flat temperature-indicating device from the vertical without the use of a case, comprising a heat-conducting carrier means with a grid of cavities thereon; and Figure 9 is a plan horizontal view taken along line 13-13 in Figure 8 revealing the heat-conducting carrier means, cavities within, transparent cover sheet means, and a bottom plate means.

Figure 10 is a plan view taken from the vertical of a transparent support member for a disposable clinical thermometer either of Figure 6 or Figures 8-9.

Figure 11 is a plan view taken from the vertical of the transparent support member of Figure 10, except in sealing engagement, with a disposable thermometer such as that shown in Figure 6 with a Fahrenheit scale from 96.0 degrees Fahrenheit to 104.8 degrees Fahrenheit graduated in 0.2 degrees Fahrenheit increments.

Figure 12 is a plan view taken from the vertical of the transparent support member of Figure 10, except in sealing engagement with a disposable thermometer, such as that shown in Figure 6 but with a Centigrade scale from 35.5 degrees Centigrade to 40.4 degrees Centigrade graduated in 0.1 degrees Centigrade increments.

Figure 13 is a partial plan view from the horizontal of a heat-conducting carrier having cavities defined therein, which cavity forms an enclosure for the novel composition of matter of this invention or for a temperature-sensitive classical composition of matter therein when such cavity is covered by a transparent cover sheet means, which is bonded to the carrier layer by an adhesive layer of polyisobutylene.

Figure 14 is a partial plan view similar to Figure 13 wherein the carrier layer is still provided with a surface layer of polyisobutylene.

Figures 1 and 2, respectively, present a partial plan view from above and the side of one embodiment of the invention showing a heat-conducting carrier means "C" of a thermometer in a Celsius system (one sub-grid showing cavities associated with 35.5"C to 37.9"C only). and a plan view from above a similar means of the same chemical thermometer in a Farenheit system in a particularly effective embodiment of the invention, to wit, a rectangular grid is formed (preferably having two sub-grids of 35.5"C to 37.9"C and 38.0 C to 40.5"C for the Celsius type and 96.0 F to 99.80F and 100.00F to 104.8"F for the Farenheit system) wherein each cavity 13 employs a construction which is clearly associated with a temperature to be determined within the range of temperatures to be tested through markings located on the side of the grid.In Figures 1 and 2, one will notice that as each cavity 13 employs the same colorant so that upon a completion of a test for the thermometer within the predetermined temperature range, one or more cavities having compositions of matter in the liquid phase will clearly be distinguished from the remaining cavities having compositions of matter in the solid phase.

The operation of the thermometer of Figure 1 (or Figure 2) is as follows: viewing Figure 5 the remote part of the handle portion "B" (not shown in Figure 1, but 35 in Figure 5) in Figure 1 is held between the fingers, and portion "C" with cavities 13 is inserted into the mouth and preferably held under the tongue for a relatively short period, to wit, approximately thirty seconds to one minute. During this time, all of the compositions of matter of the various cavities 13 which have melting points below the temperature in the mouth will melt, revealing the colorant 1 in each of said cavities to indicate a change in color visible to the naked eye.Because of the purity in nature of the melting compositions of matter such that they have a property of stable undercooling for at least several minutes, the user may simply withdraw the thermometer of Figures 1 and 2 and clearly see via the grid shown thereon his temperature to the increment of precision chosen, to wit, 0.20F or 0.1"C. Preferably. the colorant 1 for each of the cavities 13 in Figure 1 is of the same color, and all of the cavities are filled by OCNB/OBNB compositions of matter having melting points separated by equal increments of 0.2"F or 0.1"C.

Figure 3 indicates a scheme for testing temperatures of intervals of 100F using the novel compositions of matter described above (which turns from oragne 103 to red 104, for example, on melting). Here in Figure 3, transparent cover plate means 101 is in sealing engagement, preferably vacuum sealing engagement, with the heat conducting carrier means 102 and each of the peripheries of the six cavities shown. It will readily be appreciated by those skilled in the art that the novel compositions of matter can be used not only in the novel temperature-indicating device shown in Figure 1 and 2, but in other configurations as well, such as Figure 4, wherein a single cavity is employed with the same novel composition of matter of Figure 3 (that has already changed to red upon melting) to determine whether or not a material in storage has exceeded a safe temperature.

Figures 5 and 6 display in another preferred embodiment in three dimensions from a skewed angle a flat heat-conducting carrier means 37, here aluminum, with cavities 36 in a Farenheit grid (as Figure 2) from 96.0 F to 104.8"F connected to a plastic (preferably polystyrene, polypropylene, or polyethylene) handle 35. Until used, the carrier means 37 fits comfortably inside a case (preferably made of the same materials as the handle 35) 32 and by means of a roller 33 which exerts leverage downward against carrier means 37 and a layer of paper, plastic, or other retaining means 31 to prevent the carrier means 37 from being removed accidentally from case 32 unless a deliberate force is exerted on handle 35 to accomplish such removal.Although not shown in Figure 5, the end of the carrier means 37 (which is most adjacent to handle 34) is fitted with locking means so as to make a vacuum-sealing engagement between said carrier means 37 and case 32 until a deliberate force of sufficient magnitude breaks the locking means. Also, the handle 35 may be notched so as to form indentures 34 therein for a firmer grip by the user who desires to remove the carrier means 37 from the case 32.

In Figure 6, once again a transparent cover sheet means 39 in the form of a plastic transparent sheet or plastic transparent cover means fits in sealing engagement, preferably vacuum sealing engagement, with the carrier means 37 overlying and above caivities 36 and in sealing engagement with each of the peripheries of said cavities.

Figure 7 shows a horizontal section along line 11-11 of Figure 6; it is a partial plan view of several cavities having indicator means 38 in the form of a paint. Transparent cover sheet means 39 is in sealing engagement with aluminum heat conducting carrier means 37 and is in sealing engagement with each of the peripheries of the cavities; a similar bottom plate means 40 fits in sealing engagement with heat conducting carrier means 37 and is in sealing engagement with each of the peripheries of the cavities; a similar bottom plate means 40 fits in sealing engagement with heat conducting carrier means 37 so as to present the thermometer as a flat surface. The bottom plate means 40 is provided to aid the carrier means 37 in preserving structurall integrity and is co-extensive with the entire surface of carrier means 37.

In Figures 8 and 9, another preferred embodiment of the invention is disclosed for measuring temperatures at 0.2"F increments from 96.0 F to 104.80F, combining the novel compositions of matter of this invention (preferably OCNB: OBNB/pinacyanol iodide) with the cavities, only without the necessity of an indicator layer. Unlike the embodiment shown in Figure 5 and 6, the embodiment realized in Figures 8 and 9 does not have a case, and therefore is less expensive to manufacture.

Figure 8 displays a plan view of the substantially flat oral temperature indicating device as seen from above. Again, the thermometer has an aluminum heat conducting carrier means 44 of width 47 which acts not only as a main structural body of support, but at the same time provides rapid and uniform temperature distribution throughout the spatula portion "F' (having width 54) contaning grid "G" of a plurality of cavities (each of diameter 57 and spaced center-to-center with each neighbor along a horizontal "x" axis or vertical "y" axis in Figure 8 at a distance 52 apart), each cavity with the novel composition of matter and each associated with a predetermined temperature to be measured at 0.2"F increments from 96.0 F to 104.8"F, and each novel composition of matter substantially spherical void within said cavity. "Spatula" portion "F' of the device of Figure 8 is rounded for safety so that some distance 56 is maintained between the most forward row of cavities and the edge of the device.

Again in Figure 8, one will note that the aluminum heat-conducting carrier means is covered above for the entire handle "E" portion of the thermometer device by a top plastic layer 42 of width 54, preferably made out of a plastic such as polystyrene, polypropylene, or polyethylene. In Figure 9, taken along line 3-13 of Figure 8, a bottom plate means 46 of width 49 extends along the entire length 53 of the thermometer device.The top layer 42 terminates upon entering the spatula portion "F' of the thermometer device, revealing grid "G" of cavities, dark markings (preferably blue or black-painted) 45 indicating the predetermined temperature to be measured for each cavity, and a heat-sensitive transparent film cover means 43 is in sealing engagement with the carrier means 44 above, and is overlying each of said cavities to form an enclosure between the walls of each cavity and the transparent cover sheet means 43. It is important that the film cover means 43 be in tight vacuum-sealing engagement with the periphery of the carrier means 44 with each cavity to avoid loss of the composition of matter within each cavity. For that reason, as well as for appearances, some minimal distance 55 is maintained between a leading edge of a row of cavities and the edge of the thermometer device. Preferably, the heat-sensitive transparent film cover means 43 consists of bands that cover only the immediate area surrounding the cavities to avoid undue manufacturing expense. (In Figure 13, the transparent film cover means is shown in two bands, each of width 51 which covers the two rows of cavities), although it will be obvious to one skilled in the art that the heat-sensitive transparent film cover means could cover the entire spatula portion "F' of the device. The heat-sensitive transparent film cover means 43 may be put in sealing engagement with aluminum carrier means 44 through the use of a machine such as Webb Model No. 2 manufactured by Bio-Medical Sciences, Inc., of Fairfield, New Jersey.

Also in Figure 8, it will be recognized that the handle "E" has been stamped from below so as to make the device realize two ridges, ribs, or abutment 41a that protrude from above the carrier means 44 by some nominal distance which is approximately the same as width 47 of carrier means 44; Iike-.vise, the device realizes two cavities 41b in carrier means 44 that parallel the ridges 41a. As will be appreciated by those skilled in the art, the device as shown in Figures 8 and 9 is especially suitable for measuring human temperatures in the range of 96.0 F to 104.8"F, employing ortho-chloronitrobenzene and orthobromonitrobenzene in a solvent system with pinacyanol iodide in the amount of 0.05% by weight to form a thermometer with the novel compositions of matter of this invention.

Although not shown, a thermometer similar to that shown in Figures 8 and 9 could be constructed whereby the bottom plate means (46 in Figure 9) could be removed from spatula portion "F' of the device, and each of the cavities allowed to protrude entirely through the carrier means (44 in Figures 8 and 9); a bottom heat-sensitive and transparent film cover means could be placed in sealing engagement with the carrier means the peripheries of each of the cavities so that one could observe the change in color of the novel compositions of matter if the latter were employed. Also, it is obvious to one skilled in the art that ribs 41a in Figure 8 are not necessary; indeed, many minor changes in the device shown in Figures 8 and 9 could be made without departing from the spirit of the invention.

As a preferred embodiment, ribs 41a may be removed as in actual practice (TEMPA-DOT READY-STRIP"' disposable clinical thermometer of Organon Inc., West Orange, New Jersey).

Figure 10 is a plan view of a support member (preferably transparent for a disposable clinical thermometer such as depicted in Figure 6 or in Figures 8 - 9. The support member is preferably made of highly translucent polypropylene, although it will readily be noticed by one skilled in the art that the support member could, in the alternative, be constructed of any suitable malleable, soft matenal form so as to support the thermometer, yet flexible enough to avoid damaging delicate tissue of the user. The support member is intended specifically for rectal administration of the thermometer, such as for infants and the elderly or others who might otherwise not be capable of receiving oral administration properly.

The member can also be used for administration in any body cavity indicative of the temperature of the body and of sufficient dimensions to accept the member.

Referring to Figure 10 as before and now also Figures 11-12, it will be apparent that Figures 10-12 are taken from the vertical, and more particularly, that Figure 11 depicts in plan view the translucent support member, except in sealing engagement with a disposable thermometer as shown in Figure 6 with a Fahrenheit scale from 96.0 to 104.8 degrees Fahrenheit with 0.2 degrees Fahrenheit increments. Figure 12 is indentical to Figure 11, except utilizing a Centigrade scale from 35.5 degrees Centigrade to 40.4 degrees Centigrade with increments of 0.1 degrees Centigrade. Body 61 of the member acts as a bridge between the sections "H" and "I" which are adapted to fit comfortably spatula portion "F' and handle portion 42 of the disposable thermometer of Figure 8, respectively, in sealing engagement.Section "I" comprises a handle portion 64 with a ridge or indentation 63 as seen from above and facing the user in Figure 10 and above but away from the user in Figures 11-12, i.e. as if the member of Figure 10 was merely rotated on its axis 1800 to receive the Fahrenheit thermometer of Figure 11 or the Centigrade thermometer of Figure 12. Ridge 63 continues into body 61 as ridge or indentation 62 which traverses the entire support member on both sides of the member into section "H". The ridge is of sufficient width to accept the thermometer comfortably and is of such a tolerance that the disposable thermometer of Figure 6 or 8 snaps securely into fitting engagement with the member. The spatula tip 65 of section "H" is rounded smoothly, as are exterior edges of the member, in order to avoid damage to delicate tissue upon administration of the thermometer.Spatula portion "H" is suitably constructed to have a window or vacancy so that the grid of the thermometer such as grid "G" of Figure 6 is clearly seen upon removal from the source by the user.

In Figure 13 the cover layer 66 is bonded to the carrier layer 67 by an adhesive layer 68.

This adhesive layer 68 consists of a pressure-sensitive adhesive which is entirely or substantially of polyisobutylene and can be applied to the carrier layer 67 without the melt temperature of the temperature-sensitive composition 69 in the cavities being exceeded.

In Figure 14 the carrier layer 67 is still provided with a surface layer 70 of polyisobutylene. The latter serves to improve the adhesion between the pressure-sensitive polyisobutylene of the adhesive layer 68, consisting essentially of polyisobutylene, and the material of the carrier layer 67. The surface layer 70 is generally obtained by providing the carrier layer material with a thin coat of a solution of polyisobutylene in an organic solvent, e.g. hexane, and subsequently allowing the solvent to evaporate.

The temperature-sensitive composition 69 in Figures 13 and 14 is selected from the novel compositions of matter of this invention.

In yet another preferred embodiment of the invention, one may employ a circular layer or absorbent bibulous material that is impregnated with all or part of the novel composition of matter and present within the cavities of the devices of the invention. Viewed from above, as in Figure 1, each of the pockets 13 appear to be a fully coloured dot. Of course, the bibulous material must be inert to the phenomena of the novel composition of matter consists of a hydrophobic synthetic paper. One material which has been found to be especially suitable is E.I. Du Pont de Nemours & Company, spun-bonded polyolefin TYVEK (Registered Trade Mark). Other suitable materials may include aggregated inorganic powders, glass fiber paper, ordinary cellulosic paper, or polystyrene or other permeable polymeric material.An additional advantage of employing a bibulous material is that in case of accidential rupture of transparent film cover means 43 (Figure 9) but the user, for example, by the teeth, the bibulous material would prevent spillage of the liquid contents on the surrroundings.

A bibulum, loaded with the novel compositions of matter can be used for many other applications e.g. as a loading material for the cavities of temperature indicating devices when cutted, in small pieces.

Another preferred temperature indicating device consists of a layer of an absorbant material (bibilum) in which the novel composition of matter has been absorbed and which is surrounded by two transparent cover sheets in sealing engagement with each other.

Furthermore we have found that a bibulous material may act as a recrystallization promoting material, especially when the bibulum is used as a carrier for the inclusion of finely powdered insoluble nucleating agents. Such loading can be accomplished by passing the bibulum web through a dispersion of powder and then by evaporating the solvent. A punched bibulum will carry a known and predetermined quantity of the nucleating agent and may be used in the cavities of the thermometer or other device employing the novel compositions of matter.

As a preferred embodiment, we have found that film forming materials such as gelatin, polyvinyl alcohol, and water soluble cellulose derivatives are good barriers for containing small particles or droplets of the novel compositions of matter of our invention,especially the compositions wherein OCNB/OBNB is the solvent. After this form of microencapsulation, a dry granular material is formed that is easily adaptable to various machinery processes. A typical micro-encapsulated novel composition would be an OCNB/OBNB solution containing 0.035 weight percent pinacyanol iodide surrounded by a layer of gelatin coacervated with acacia and fixed with glutaraldehyde. The use of these microencapsulated novel compositions would permit application to temperature-sensing devices with more flexibility.

For example, the microencapsulated novel compositions may be formulated into a pressure-sensitive adhesive from which a temperature indicating tape could be made.

Microencapsulated novel compositions could be incorporated into printing presses to permit temperature sensing regions of unlimited geometry including temperature-sensitive messages.

Exposure of the clinical themometers above 35.5"C will make them useless for further temperature measurement unless an effective method of recrystallization is employed.

Often protective packaging during shipments will be necessary. We have discovered, that protective packaging of heat labile goods can be greatly improved by using certain salts, notablv sodium sulfate decahydrate, e.g. Glauber's salt, as the refrigerant. Glauber's salt acts as a refrigerant as follows: the melting point of Glauber's salt is 32.8"C. The TEMPA-DOT READY-STRIP begins to indicate temperature at 35.2"C. When TEMPA DOT READY-STRIP thermometers are packaged with Glauber's salt and exposed to high temperatures, for example 50"C, the temperature of the package rises until it reaches 32.28"C. At that temperature the Glauber's salt begins to melt and absorb heat (energy) at a capacity of about 54 cal/gram.The package will remain at about 32"C until the salt has been molten completely.

Besides sodium sulfate decahydrate calcium chloride hexahydrate is suitable as well.

Moreover, organic compounds having a melting point of 32"C, e.g. OCNB, may be used.

Generally the refrigerant should be selected as one having a melting point 3-5"C below the labile temperature.

A preferred method of package of the refrigerant consists of absorbing the molten refrigerant into a bibulous material such as open cell foam, paper, natural or synthetic sponge and the like, sealed to exclude contamination and, for hydrated salts, water vapor exchange by enclosing the structure in a flexible plastic bag, for example.

An example of such a packaged refrigerant is sodium sulfate decahydrate absorbed into a block of open cell phenol-Formaldehyde foam and contained in a polyethylene bag closed by heat sealing. When placed in an insulated container, the refrigerant block protects the contents from exposure to high temperature in the same fashion as the unsupported Glauber's salt.

Although the invention has been described with reference to specific embodiments above, numerous variations and modifications will become evident to those skilled in the art, without departing from the scope and spirit of the invention as described above defined in the appended claims, and as shown in the following examples.

Example I A solution of about 0.05 mass % of pinacyanol iodide in a mixture of orthochloronitrobenzene and ortho-bromonitrobenzene (25 mass % of orthochloronitrobenzene and 75 mass % of ortho-bromonitrobenzene) was prepared by adding the pinacyanol iodide into a beaker containing an amount of liquid solvent mixture at about 50"C. After dissolution of the pinacyanol iodide by mechanical stirring a novel composition of matter was obtained. This blue liquid was cooled and at about 38"C, using artificial nucleating, the blue liquid solution changed to a solid which was light greenish-pink.

Heating the solidified material up to its melting point again results in obtaining a blue liquid. This example demonstrates that a novel compositions of matter employing a member of group I changes colour while passing from the liquid state to the solid state, or conversely.

Example II A solution of about 0.05 mass % of chlorophenol red in dibenzofurane was prepared by adding the chlorophenol red to liquid dibenzofurane at 950C. After dissolution of the chlorophenol red a yellow liquid was obtained. After this liquid had been cooled to about 87"C, it began to solidify and when the solidification was complete a red coloured solid was obtained. Upon heating the red solid, it changed back into a yellow liquid.

This example demonstrates the use of a group I member dissolved in a heterocyclic solvent to obtain a colour change while passing from the liquid state to the solid state, or conversely.

Example III A solution of 0.0375 mass % of chlorophenol blue and 0.0125 mass % of ethyl red was prepared in a mixture of orthhobromonitrobenzene and ortho-chloronitrobenzene (mass ratio 3:1) in the same way as described in Example I. On cooling and artifical nucleation the red liquid solution changed into a yellow solid at 37.50C. Upon heating, the yellow solid turned red again at 38.0 C.

This Example demonstrates that the combination of an acid with a pK of less than about 4 and a basic indicator in a suitable aromatic solvent system will change colour upon a corresponding change from the liquid state to the solid state, or conversely.

Example IV In the same way as described in Example I a solution of 0.037 mass % naphthalenesulphonic acid and 0.013 mass % of ethyl violet was prepared in a mixture of ortho-bromonitrobenzene and ortho-chloronitrobenzene (mass ratio 3:1). Whereas the liquid solution was green, the solid solution obtained by artifical nucleation at 380C was yellow. Upon heating the composition to its melting point a green liquid was obtained. This Example demonstrates that the combination of an acid with a pK of less than about 2 and an amino-triphenylmethane dye will change colour while passing from the liquid state to the solid state, or conversely.

Example V This Example demonstrates the use of a combination of a dye having a molecular structure containing a lactone group and an acid having a pK of about 8 to about 12. In the same way as described in Example I a composition of matter was prepared by dissolving 0.05 mass % crystal-violetlactone and 0.05 mass % phenol in a mixture of orthobromonitrobenzene and orth-chloronitrobenzene (mass ratio 3:1). The liquid solution was yellow and turned blue when it had completely solidified at 37.50C by artificial nucleation.

Upon heating the compoition it become yellow again.

Example VI (comparative) This Example deals with a dye falling beyond the scope of this invention.

In the same way as described in Example I a solution was prepared of Fast Blue Salt B in a mixture of ortho-bromonitrobenzene and ortho-chloronitrobenzene (mass ratio 3:1).

The colour of the liquid was yellow and did not change after complete crystallization of the solvent.

Example VII This Example gives dyes tested for their suitability as a group I member in various solvents at different concentrations. The results are given in Table I.

TABLE I Concentration Colour No. Class Dye Solvent % (m/m) liquid solid 1 nitroso Irgalith green BLN OBNB/OCNB 0,05 *yellowish green yellowish green dyes (Ciba-Geigy) 3 : 1 2 nitroso Naphtol green B OBNB/OCNB 0,2 *green green dyes C.I. Acid green 1 3 @ 1 0,05 light green light green C.I. No. 10020 0,005 yellow yellow 3 nitroso 1-nitroso- 2-naphtol OBNB/OCNB 0,2 brown brown dyes C.I. Mordant green 4 3 : 1 0,05 yellowish brown yellowish brown C.I. No. 10005 0,05 yellow yellow 4 nitro dyes Naphtol yellow OBNB/OCNB 0,05 *yellow yellow C.I. Acid yellow 1 3 @ 1 C.I. No. 10316 5 nitro dyes Artisil yellow F-L OBNB/OCNB 0,05 *yellow yellow (Sandoz) 3 : 1 C.I. Disperse yellow 42 C.I. No. 10338 6 nitro dyes Aurantia OBNB/OCNB 0,2 *red dark orange CI. No. 10360 3 @ 1 7 azo dyes Savinyl red BLSN OBNB/OCNB 0,05 red red (Sandoz) 3 : 1 C.I.Solvent red 90 8 azo dyes Savinyl fire red OBNB/OCNB 0,05 red red 3 GLS (Sandox) 3 : 1 C.I. Solvent red 124 9 azo dyes Orasol orange RLN OBNB/OCNB 0,05 red orange -red (Ciba - Geigy) 3 @ 1 lauryl 0,05 orange orange alcohol *not completely dissolved TABLE I (cont. .) Concentration Colour No. Class Dye Solvent % (m/m) liquid solid 10 monoazo 4-(p-ethoxyphenyl- OBNB/OCNB 0.2 brownish red dark yellow azo)-m-phenylene 3 : 1 0,05 reddish orange dark yellow diamine mono- 0,005 yellow yellow hydrochloride lauryl 0,2 orange orange alcohol 11 monoazo Orasol navy blue OBNB/OCNB 0,2 dark blue bluish black (Ciba-Geigy) 3 : 1 0,05 dark blue greenish blue C.I. Solvent blue 53 0,005 bluish green green formamide 0,2 dark blue dark blue 0,05 dark blue dark blue 0,005 blue blue lauryl 0,2 dark blue dark blue alcohol 0,05 dark blue blue 0,005 blue light blue 12 monoazo Organol orange OBNB/OCNB 0,2 reddish orange reddish orange (Ugine Kuhlmann) 3 : 1 0,05 orange oramge C.I. Solvent orange 2 0,005 orange orange C.I. No. 12100 formamide 0,2 dark orange orange lauryl 0,2 dark orange dark orange alcohol 0,05 orange orange 0,005 orange light orange 13 monoazo Janus green OBNB/OCNB 0,2 dark blue dark blue C.I. No. 11050 3 : 1 0,05 dark blue green 0,005 green green formamide 0,2 dark blue dark blue 0,05 dark blue dark blue 0,005 blue blue lauryl 0,2 dark blue blue alcohol 0,05 blue light blue 0,005 light blue nearly colourless *not completely dissolved TABLE I (cont...) Concentration Colour No.Class Dye Solvent % (m/m) liquid solid 14 monoazo Irgalith red P4R OBNB/OCNB 0,2 orange-red red (Ciba-Geigy) 3 @ 1 0,05 dark orange pink C.I. Pigment red 3 0,005 orange orange-yellow C.I. No. 12120 formamide 0,2 *red red 15 monoazo Azophloxin OBNB/OCNB 0,2 dark red dark red C.I. Acid red 1 3 @ 1 0,05 reddish brown reddish brown Food red 10 0,005 yellow yellow C.I. No. 18050 16 monoazo Dimethyl yellow OBNB/OCNB 0,2 reddish orange orange C.I. Solvent yellow 2 3 @ 1 0,05 orange orange C.I. No. 11020 0,005 orange dark yellow lauryl 0,2 yellowish orange dark yellow alcohol 0,05 dark yellow yellow 0,005 yellow light yellow naphthalene 0,05 orange dark yellow 17 monoazo Fast yellow OBNB/OCNB 0,2 orange dark yellow C.I. Acid yellow 9 3 @ 1 0,05 dark yellow yellow Food yellow 2 0,005 yellow yellow C.I.No. 13015 lauryl 0,2 *orange yellow alcohol 18 monoazo Methyl red, OBNB/OCNB 0,2 red red sodium salt 3 : 1 0,05 red orange-brown C.I. Acid red 2 0,005 dark orange orange C.I. No. 13020 lauryl 0,2 reddish orange orange-yellow alcohol 0,05 reddish orange light brown 0,005 orange light orange naphthalene 0,05 orange orange *not completely dissolved TABLE I (cont...) Concentration Colour No. Class Dye Solvent % (m/m) liquid solid 19 monoazo Alizarin yellow R OBNB/OCNB 0,2 *greenish brown brownish yellow C.I. Mordant orange 1 3 : 1 C.I. No. 14030 20 monoazo Eriochrome black T OBNB/OCNB 0,2 *dark brown brown C.I. Mordant black 11 3 : 1 C.I. No. 14645 21 monoazo Chromotrope 2R OBNB/OCNB 0,2 *green light green C.I. Acid red 29 3 : 1 Mordant blue 80 C.I. No. 16570 22 monoazo Ponceau 6R OBNB/OCNB 0,2 *dark brown yellowish brown C.I. Food red 8 3 @ 1 C.I.No. 16920 23 monoazo Titan yellow OBNB/OCNB 0,2 yellow yellow C.I. Direct yellow 9 3 @ 1 0,05 yellow yellow C.I. No. 19540 0,005 yellow yellow 24 monoazo Yellow orange S OBNB/OCNB 0,2 red orange C.I. Food yellow 3 3 : 1 0,05 orange dark yellow C.I. No. 15985 0,005 yellow yellow 25 monoazo Brilliant Ponceau 5R OBNB/OCNB 0,2 *brownish red light brown C.I. Acid red 18 3 : 1 0,05 brownish yellow brownish yellow Food red 7 0,005 yellow yellow C.I. No. 16255 26 monoazo Chrysoidin G OBNB/OCNB 0,2 red ochre C.I. Basic orange 2 3 @ 1 0,05 reddish iorange dark yellow C.I. No. 11270 0,005 dark yellow light yellow lauryl 0,2 red red alcohol 0,05 orange-red reddish orange 0,005 dark yellow yellow naphthalene 0,05 orange orange *not completely dissolved TABLE I (cont...) Concentration Colour No.Class Dye Solvent % (m/m) liquid solid 27 monoazo Chrysoidin R OBNB/OCNB 0,2 *dark orange-red dark orange-red C.I. Basic orange 1 3 @ 1 C.I. No. 11320 28 monoazo Eriochrome black A OBNB/OCNB 0,2 black dark green C.I. Mordant black 1 3 @ 1 0,05 moss green moss green C.I. No. 15710 0,005 light green light green 29 monoazo Benzyl orange OBNB/OCNB 0,05 deep yellow yellow 3 @ 1 lauryl 0,05 orange yellow alcohol naphthalene 0,05 light orange colourless 30 monoazo Ponceau G,R,2R OBNB/OCNB 0,2 *brownish red brownish yellow C.I. Acid red 26 3 @ 1 Food red 5 C.I. No. 16150 31 monoazo Chromolan yellow OBNB/OCNB 0,2 *light brown yellow C.I. Acid yellow 54 3 @ 1 0,05 yellow yellow C.I. No. 19010 0,005 yellow yellow 32 disazo Fat red BS (Sandoz) OBNB/OCNB 0,2 dark red dark red C.I. Solvent red 24 3 @ 1 0,05 dark red brownish red C.I.No. 26105 0,005 light red light red lauryl alcohol 0,05 dark red red 33 disazo Sudan red B OBNB/OCNB 0,2 dark red dark red C.I. Solvent red 25 3 @ 1 0,05 dark red dark rked C.I. No. 26110 0,005 red orange lauryl alcohol 0,2 *dark red dark red 0,05 red red 0,005 light red light red *not completely dissolved TABLE I (cont...) Concentration Colour No. Class Dye Solvent % (m/m) liquid solid naphthalene 0,05 vermilion dark red 34 disazo Bismarck brown G OBNB/OCNB 0,2 very dark green dark green C.I. Basic brown 1 3 @ 1 0,05 brownish green dark green C.I. No. 21000 0,005 light green light green lauryl alcohol 0,2 *dark green dark green naphthalene 0,05 yellow light brown 35 disazo Fat black OBNB/OCNB 0,2 black black C.I. Solvent black 3 3 @ 1 0,05 black black C.O.No. 26150 0,005 very dark green dark green 0,0005 green light green lauryl 0,2 black black alcohol 0,05 black dark blue 0,005 dark blue glue 0,005 blue light blue 36 disazo Resorcin brown OBNB/OCNB 0,2 *brownish red reddish brown C.I. Acid Orange 24 3 @ 1 0,05 brownish yellow brownish yellow C.I. No. 20170 0,005 yellow yellow 37 disazo Benzo fast pink 2BL OBNB/OCNB 0,2 *green light green C.I. Direct red 75 3 @ 1 C.I. No. 25380 38 disazo Oil red EGN OBNB/OCNB 0,2 vermilion dark red C.I. Solvent red 26 3 @ 1 0,05 vermilion dark red C.I. No. 26120 0,005 red red 39 disazo Tryptan blue OBNB/OCNB 0,2 light green light green C.I. Direct blue 14 3 @ 1 0,05 light green light green C.I. No. 23850 0,005 light green light green *not completely dissolved TABLE I (cont...) Concentration Colour No.Class Dye Solvent % (m/m) liquid solid 40 disazo Brilliant yellow OBNB/OCNB 0,2 orange orange C.I. Direct yellow 4 3 : 1 0,05 dark yellow dark yellow C.I. No. 24890 0,005 yellow yellow 41 trisazo Chlorazol black E OBNB/OCNB 0,05 *greenish yellow greenish yellow C.I. Direct black 38 3 : 1 C.I. No. 30235 42 trisazo Diamingreen B OBNB/OCNB 0,2 green light green C.I. Direct green 6 3 : 1 0,05 light green light green C.I. No. 30295 0,005 yellowish green yellowish green lauryl alcohol 0,2 *green light green 43 trisazo Direct green G OBNB/OCNB 0,2 *green light green C.I. Direct green 8 3 @ 1 0,05 light green light green C.I. No. 30315 0,005 yellow yellow 44 azoic Fast red salt 3GL OBNB/OCNB 0,2 yellowish orange dark yellow C.I. No. 37040 3 : 1 0,05 very dark yellow dark yellow 0,005 yellow yellow 45 azoic Fast blue salt BB OBNB/OCNB 0,2 brownish yellow greenish yellow C.I. No. 37175 3 @ 1 0,05 brownish yellow greenish yellow 0,005 yellow yellow 46 azoic Fast garnet salt GBC OBNB/OCNB 0,2 dark brown dark brown C.I. No. 37210 3 @ 1 0,05 brownish red brownish yellow 0.005 yellow yellow 47 azoic Fast blue salt B OBNB/OCNB 0,2 yellow yellow C.I. No. 37235 3 @ 1 0,05 yellow yellow 0,005 yellow yellow *not completely dissolved TABLE I (cont...) Concentration Colour No. Class Dye Solvent % (m/m) liquid solid 48 stilbene Carta yellow G 180% OBNB/OCNB 0,2 *brownish yellow yellow (Sandoz) 3 : 1 0,05 yellow yellow C.I. Direct yellow 11 0,005 yellow yellow C.I. No. 40000 49 Diphenyl- Auramin OBNB/OCNB 0,2 yellow yellow methane C.I. Basic yellow 2 3 : 1 0,05 yellow yellow C.I. No. 41000 0,005 yellow yellow 50 triaryl- Malachite green OBNB/OCNB 0,2 green green green methane C.I. Basic green 4 3 : 1 0,05 green green C.I.No. 42000 0,005 green green formamide 0,2 dark green dark green 0,05 green green 0,005 light green light green 51 triaryl- Brilliant green OBNB/OCNB 0,2 green green methane C.I. Basic green 1 3 : 1 0,05 green green C.I. No. 42040 0,005 green green formamide 0,2 dark green dark green 0,05 green green 0,005 light green light green 52 triaryl- Methyl violet OBNB/OCNB 0,2 violet violet methane C.I. Basic violet 1 3 : 1 0,05 bluish violet violet C.I. No. 42535 0,005 bluish violet violet formamide 0,2 violet violet 0,05 violet violet 0,005 violet violet *not completely dissolved TABLE I (cont...) Concentration Colour No. Class Dye Solvent % (m/m) liquid solid 53 triaryl- Xylene cyanol FF OBNB/OCNB 0,2 blue blue methane C.I.No. 43535 3 @ 1 0,05 blue light blue 0,005 green light green formamide 0,2 blue dark blue 0,05 blue blue 0,005 blue blue 54 triaryl Erioglaucine OBNB/OCNB 0,2 blue greenish blue methane C.I. Acid blue 9 3 : 1 0,05 blue green Food blue 2 0,005 green light green C.I. No. 42090 lauryl 0,2 blue light blue alcohol 0,05 light blue light blue 0,005 light blue light blue naphthalene 0,05 greenish blue greenish blue 55 triaryl- Fuchsin NB OBNB/OCNB 0,2 dark red dark red methane C.I. Basic violet 2 3 : 1 0,05 dark red reddish brown C.I. No. 42520 0,005 pinkish violet greenish yellow lauryl 0,2 dark purple dark purple alcohol 0,05 pinkish purple purple 0.005 pink pink naphthalene 0,05 *purple light purpleviolet 56 triaryl- Fuchsin OBNB/OCNB 0,2 dark reddish dark violet methane C.I. Basic Violet 14 3 @ 1 violet C.I.No. 42510 0,05 dark red brownish red 0,005 pinkish violet greenish beige *not completely dissolved TABLE I (cont...) Concentration Colour No. Class Dye Solvent % (m/m) liquid solid lauryl 0,2 dark purple dark purple alcohol 0,05 purple purple 0,005 pink pink naphthalene 0,05 *red light brown 57 triaryl- Parafuchsin OBNB/OCNB 0,2 dark red dark brown methane C.I. Basic red 9 3 : 1 f0,05 red light brown C.I. No. 42500 0,005 light red orange-yellow lauryl 0,2 red red alcohol 0,05 purple-red lilac purple 0,005 lilac lilac naphthalene 0,05 *dark purple light purple 58 triaryl- Aurintricarboxylic OBNB/OCNB 0,2 *reddish orange orange brown methane acid, ammonium salt 3 : 1 C.I. Mordant violet 39 C.I. No. 43810 59 triaryl- Patent blue OBNB/OCNB 0,2 very dark blue dark blue methane C.I.Acid blue 1 3 : 1 0,05 dark blue bluish green Food blue 3 0,005 green light green C.I. No. 42045 60 triaryl- Ethyl violet OBNB/OCNB 0,2 dark blue dark blue methane C.I. Basic violet 4 3 : 1 0,05 blue blue C.I. No. 42600 0,005 blue blue 61 triaryl- Victoria blue R OBNB/OCNB 0,2 dark blue dark greenish blue methane C.I. Basic blue 11 3 @ 1 0,05 dark blue dark bluish green C.I. No. 44040 0,005 dark blue bluish green 62 triaryl- Irgalith violet MNC OBNB/OCNB 0,2 bluish violet bluish violet methane (Ciba-Geigy) 0,05 blue blue C.I. Pigment violet 3 0,005 blue blue C.I. No. 42535 : 2 TABLE I (cont...) Concentration Colour No. Class Dye Solvent % (m/m) liquid solid formamide 0,2 bluish violet violet 0,05 bluish violet bluish violet 0,005 bluish violet bluish violet 63 triaryl- Crystal violet OBNB/OCNB 0,2 bluish violet violet methane C.I.Basic violet 3 3 : 1 0,05 blue blue violet C.I. No. 42555 0,005 blue blue formamide 0,2 violet violet 0,05 violet bluish violet 0,005 violet bluish violet 64 triaryl- Irgalith blue TNC OBNB/OCNB 0,2 blue blue methane (Ciba - Geigy) 3 @ 1 0,05 blue blue C.I. Pigment blue 1 0,005 blue bluish green C.I. No. 42595 # 2 formamide 0,2 blue blue 0,05 blue blue 0,005 blue blue 65 Xanthene Phloxin B OBNB/OCNB 0,2 orange pinkish oragne C.I. Acid red 92 3 : 1 0,05 yellowish orange yellowish orange C.I. No. 45410 0,005 yellow yellow formamide 0,2 orange-red orange-red 0,05 reddish orange orange-brown-red 0,005 pink pink lauryl alcohol 0,05 pink light pink 66 Xanthene Fluorescein, OBNB/OCNB insoluble sodium salt 3 : 1 C.I. Acid yellow 73 formamide 0,2 yellow orange-yellow C.I. No. 45350 0,05 yellow yellow 0,005 yellow yellow TABLE I (cont...) Concentration Colour No.Class Dye Solvent % (m/m) liquid solid lauryl 0,05 *yellow yellow alcohol 67 Xanthene Rose bengale OBNB/OCNB insoluble C.I. Acid red 94 3 : 1 C.I. No. 45440 formamide 0,2 dark red dark red 0,05 violet-red violet-red 0,005 pinkish violet pinkish violet 68 Xanthene Rhodamine B OBNB/OCNB 0,2 red violet C.I. Basic violet 10 3 : 1 0,05 pinkish red violet C.I. No. 45170 0,005 pinkish red violet-pink-red formamide 0,2 red reddish violet 0,05 orange-red pinkish red 0,005 pinkish orange pink lauryl alcohol 0,05 violet-red pinkish violet naphthalene 0,05 dark purple-red lilac (fluorescent) 69 Xantene Rhodamine B Base OBNB/OCNB 0,2 red red C.I. Solvent red 49 3 : 1 0,05 red deep pink C.I. No. 45170 : 1 0,005 light red pink 70 Xanthene Rhodamine 6 G OBNB/OCNB 0,2 red violet-red C.I. Basic red 1 3 : 1 0,05 red reddish violet C.I.No. 45160 0,005 orange pinkish red formamide 0,2 orange-red purple-red 0,05 orange orange-pink 0,005 orange-pink orange-pink lauryl alcohol 0,05 pinkish orange pink *not completely dissolved TABLE I Cont'd..

Concentration Colour No. Class Dye Solvent % (m/m) liquid solid 71 Xanthene Pyronin G OBNB/OCNB 0,2 reddish brown violet-brown C.I. No. 45005 3 @ 1 0,05 red brown 0,005 pink pinkish red formamide 0,2 red reddish violet 0,05 greenish red brownish red 0,005 pink pink lauryl alcohol 0,05 pink pinkish violet 72 Xanthene Irgalith magenta TCB OBNB/OCNB 0,2 red violet-red (Ciba - Geigy) 3 @ 1 0,05 red violet-red C.I. Pigment Violet 2 0,005 red pink C.I. No. 47175 formamide 0,2 reddish orange violet-red 0,05 orange orange-pink 0,005 orange-pink pink lauryl alcohol 0,05 *orange-pink light-pink 73 Xanthene Irgalith pink TYNC OBNB/OCNB 0,2 red violet-red (Ciba - Geigy) 3 @ 1 0,05 orange-red red C.I. Pigment red 81:1 0,005 orange red C.I. No. 445160 : 2 formamide 0,2 orange brownish red 0,05 yellowish orange pinkish red 0,005 pink pink lauryl alcohol 0,5 *orange-pink light pink 74 Xanthene Eosin scarlet OBNB/OCNB 0,05 *yellow yellow C.I. Acid red 91 3 : 1 C.I. No. 45400 formamide 0,05 *pinkish orange orange lauryl alcohol 0,05 *orange orange-pink *not completely dissolved TABLE I Cont'd...

Concentration Colour No. Class Dye Solvent % (m/m) liquid solid 75 Xanthene Eosin yellowish OBNB/OCNB 0,05 *yellow yellow C.I. Acid red 87 3 : 1 C.I. No. 45380 formamide 0,05 orange orange lauryl alcohol 0,05 orange pinkish orange 76 Xanthene Erythrosin, extra OBNB/OCNB 0,05 *yellow yellow bluish 3 : 1 C.I. Acid red 51 formamide 0,05 orange-pink pinkish orange C.I. No. 45430 lauryl alcohol 0,05 pinkish orange pinkish red 77 Xanthene 4',5'-Dibromo- OBNB/OCNB 0,05 yellow orange fluorescein 3 : 1 C.I. Acid orange 11 C.I. No. 45370 formamide 0,05 orange-yellow orange-yellow lauryl alcohol 0,05 orange-yellow orange-yellow 78 Xanthene Ethyl eosin OBNB/OCNB 0,05 *reddish orange orange C.I. Solvent red 45 3 : 1 C.I. No. 45386 formamide 0,05 pinkish orange orange-pink lauryl alcohol 0,05 *orange-pink pink 79 Xanthene Gallein OBNB/OCNB 0,05 *yellowish brown brown C.I. Mordant violet 25 3 : 1 C.I.No. 45445 formamide 0,05 brownish orange light brown lauryl alcohol 0,05 brownish orange violet *not completely dissolved TABLE I Cont'd..

Concentration Colour No. Class Dye Solvent % (m/m) liquid solid 80 Xanthene Phloxine OBNB/OCNB 0,2 red brownish red C.I. Acid red 98 3 @ 1 0,05 deep brownish brownish yellow C.I. No. 45405 yellow 0,005 yellow yellow 81 Xanthene Erythrosin yellowish OBNB/OCNB 0,2 @red brownish red blend 3 : 1 0,05 brownish yellow light brownish red C.I. Acid red 95 0,005 yellow yellow C.I. No. 45425 82 Xanthene Cyanosin B OBNB/OCNB 0,2 orange orange C.I. No. 45420 3 : 1 0,05 orange orange 0,005 light orange yellowish 83 sulphone- Cresol red OCNB 0,05 yellow red phthaleine dioxane 0,05 yellow reddish orange water 0,05 yellow red (deep cooling) naphthalene 0,05 light yellow red TABLE I Cont'd...

84 sulphone- chlorophenol red OBNB/OCNB 0,05 yellow red phthaleine 3 : 1 OCNB 0,05 yellow red dioxane 0,05 yellow reddish orange paraffin 0,05 nearly colourless pink para-dichloro- 0,05 pink red benzene water 0,05 yellow red (deep cooling) naphthalene 0,05 nearly colourless red o iodonitro 0,05 brown orange benzene m iodonitro- 0,05 yellow red benzene p iodonitro- 0,05 brown red benzene p chloronitro- 0,05 yellow red benzene m bromonitro- 0,05 yellow red benzene p bromonitro- 0,05 orange red benzene p dibromo- 0,05 pink red benzene p toluic acid 0,05 yellow red 2 naphtol 0,05 brown red indole 0,05 orange reddish brown dibenzofurane 0,05 yellow red *not completely dissolved TABLE I Cont'd..

Concentration Colour No. Class Dye Solvent % (m/m) liquid solid 85 sulphone- chlorophenol blue OBNB/OCNB 0,05 yellow yellowish orange phthalein 3 @ 1 86 sulphone- bromophenol blue OBNB/OCNB 0,05 yellow yellowish orange phthalein 3 @ 1 87 sulphone- bromocresol purple OBNB/OCNB 0,05 yellow orange-yellow phthalein 3 @ 1 88 sulphone- chlorocresol green OBNB/OCNB 0,05 yellow yellowish orange phthalein 3 @ 1 89 acridine Acridine yellow OBNB/OCNB 0,05 yellow yellow C.I. No. 46025 3 @ 1 90 acridine Coriphosphine O OBNB/OCNB 0,2 deep violet brown C.I. Basic yellow 7 3 @ 1 0,05 deep violet greenish brown C.I. No. 46020 0,005 brown greenish beige 91 acridine Acriflavine OBNB/OCNB 0,2 orange dark yellow C.I. No. 46000 3 @ 1 0,05 yellowish orange yellow 0,005 yellow light yellow 92 acridine Acridine orange OBNB/OCNB 0,05 brownish orange brownish orange C.I. Basic orange 14 3 : 1 C.I.No. 46005 OCNB 0,05 red orange 0,01 orange yellow lauryl alcohol 0,05 yellowish orange orange 93 quinoline Terasil yellow 2GW OBNB/OCNB 0,05 *yellow yellow C.I. Disperse yellow 54 3 @ 1 C.I. No. 47020 *not completely dissolved TABLE I Cont'd...

Concentration Colour No. Class Dye Solvent % (m/m) liquid solid 94 quinoline Quinoline yellow OBNB/OCNB 0,2 dark yellow dark yellow C.I. Solvent yellow 33 3 : 1 0,05 yellow yellow C.I. No. 47000 0,005 yellow yellow 95 quinioline Pinacyanolchloride OCNB 0,05 blue violet 0,005 blue green OBNB/OCNB 3 : 1 0,05 blue violet-blue 96 quinoline Pinacyanolbromide OBNB/OCNB 0,05 blue violet 3 : 1 97 quinoline Pinacyanoliodide OBNB/OCNB 0,05 blue light greenish pink 3 : 1 naphthalene 0,05 blue light blue n-tetracosane 0,025 light blue light violet dibenzofurane 0,05 blue light bluish green 1-tetradecanol 0,05 blue light violet 0,025 blue light grey stearic acid 0,025 blue light greyish violet indole 0,025 dark blue blue 98 quinoline Quinaldine red OBNB/OCNB 0,05 light brown purple-red 3 : 1 naphthalene 0,05 deep purple-red beige 99 quinoline Cryptocyanine OBNB/OCNB 0,05 green bluish green 3 : 1 p-dichlorobenzene 0,05 light blue nearly colourless naphthalene 0,05 green dark blue OCNB 0,05 dark green bluish green 100 quinoline 1,1'-Diethyl-2,2'- OBNB/OCNB 0k05 red brownish yellow cyanine iodide 3 : 1 naphthalene 0,05 deep red reddish pink OCNB 0,05 deep reddish red violet TABLE I Cont'd Concentration Colour No.Class Dye Solvent % (m/m) liquid solid 101 quinoline 2(p-dimethylamino- OBNB/OCNB 0,05 red orange styryl)-1-ethyl- 3 : 1 pyridinium iodide naphthalene 0,05 red orange OCNB 0,05 red orange 102 quinoline 3,3'-Diethylthia- OBNB/OCNB 0,05 bluish green blue dicarbocyanine 3 @ 1 iodide 103 quinoline Ethyl red OBNB/OCNB 0,05 red red@2 3 : 1 p-dichlorobenzene 0,05 violet light violet 104 quinoline Dicyanine A OBNB/OCNB 0,05 green blue green 3 @ 1 105 quinoline Merocyanine 540 OBNB/OCNB 0,05 purple rose 3 @ 1 106 quinoline Neocyanine OBNB/OCNB 0,05 green yellow green 3 : 1 107 thiazole Thioflavine TCN OBNB/OCNB 0,2 @yellow yellow C.I. Basic yellow 1 3 @ 1 C.I. No. 49005 108 azine Neutral red (chloride) OBNB/OCNB 0,2 red reddish brown C.I. Basic red 5 3 @ 1 0,05 red reddish orange C.I.No. 50040 0,005 red light orange formamide 0,2 red dark brown 0,05 orange-red reddish brown 0,005 orange yellow orange not completely dissolved *2after one week storage at room temperature nearly colourless TABLE I Cont'd Concentration Colour No. Class Dye Solvent % (m/m) liquid solid lauryl 0,2 red brown alcohol 0,05 red reddish orange 0,005 reddish orange pink naphthalene 0,05 red dark brown 109 azine Neutral red (iodide) OBNB/OCNB 0,05 deep red reddish brown 3 : 1 0,005 red brownish orange 110 azine Nigrosine OBNB/OCNB 0,2 dark grey-blue dark grey-black C.I. Acid black 2 3 @ 1 0,05 blue grey blue C.I. No. 50420 0,005 greenish greenish formamide 0,2 dark violet dark violet-black 0,05 dark violetk dark violet 0,005 violet violet lauryl 0,2 grey-blue-violet dark violet alcohol 0,05 blue-violet violet 0,005 violet violet 111 azine Savinyl blue B OBNB/OCNB 0,2 dark blue dark blue (Sandoz) 3 @ 1 0,05 blue light blue C.I. Acid blue 59 0,005 greenish blue green C.I. No. 50315 formamide 0,2 dark blue dark blue 0,05 dark blue dark blue 0,005 blue blue lauryl 0,2 dark blue blue alcohol 0,05 dark blue blue 0,005 blue light blue 112 azine Orasol blue BLN OBNB/OCNB 0,2 dark blue dark blue (Ciba - Geigy) 3 : 1 0,05 blue blue C.I. Solvent blue 49 0,005 greenish blue greenish blue TABLE I Cont'd Concentration Colour No.Class Dye Solvent % (m/m) liquid solid formamide 0,2 dark blue dark blue 0,05 dark blue dark blue 0,005 blue blue lauryl 0,2 dark blue dark blue alcohol 0,05 blue blue 0,005 light blue blue 113 azine Safranin O OBNB/OCNB 0,05 *red brownish red C.I. No. 50240 3 : 1 0,005 *orange light brown formamide 0,05 red red lauryl 0,05 red orange-brown alcohol 0,005 pinkish red pink 114 azine Azocarmin G OBNB/OCNB 0,05 *yellow brownmish yellow C.I. Acid red 101 3 : 1 C.I. No. 50085 formamide 0,05 violet red violet red lauryl alcohol 0,05 *violet pink violet pink 115 azine Azocarmine BX (B) OBNB/OCNB 0,2 red red C.I. Acid red 103 3 : 1 0,05 red beige C.I. No. 50090 0,005 yellow yellow lauryl alcohol 0,2 red pink 0,05 purple light purple 0,005 pink pink naphthalene 0,05 dark red red 116 zaine Phenosafranine OBNB/OCNB 0,2 dark red dark red C.I.No. 50200 3 : 1 0,05 red beige 0,005 yellow yellow *not completely dissolved TABLE I Cont'd Concentration Colour No. Class Dye Solvent % (m/m) liquid solid laury 0,2 dark red purple red alcohol 0,05 dark pink dark pink 0,005 pink pink naphthalene 0,05 pink pink 117 azine Rhoduline violet OBNB/OCNB 0,2 violet deep reddish violet C.I. No. 50215 3 : 1 0,05 violet reddish violet 0,005 red violet rfed 118 oxazine Deorlene blue 5G OBNB/OCNBset bluish green bluish green (Ciba) 3 : 1 C.I. Basic blue 3 C.I. No. 51004 119 oxazine Solophenyl brilliant OBNB/OCNB 0,05 *yellow greenish blue BL (Ciba-Feigy) 3 : 1 C.I. Direct blue 106 formamide 0,05 dark blue dark blue C.I. No. 51300 120 oxazine Nile blue A OBNB/OCNB 0,05 *greenish blue grey-green-blue C.I. Basic blue 12 3 : 1 C.I. No. 51180 121 oxazine Gallocyanine OBNB/OCNB 0,2 dark blue dark green C.I.

Mordant blue 10 3 : 1 0,05 bluish green light green C.I. No. 51030 0,005 green greenish yellow 122 oxazine Gallamine blue OBNB/OCNB 0,2 *greenish blue light green C.I. Mordant blue 15 3 : 1 C.I. No. 51045 123 oxazine Celestine blue OBNB/OCNB 0,2 blue green C.I. Mordant blue 14 3 : 1 0,05 blue light green C.I. No. 51050 0,005 green greenish yellow *not completely dissolved TABLE I Cont'd...

Concentration Colour No. Class Dye Solvent % (m/m) liquid solid 124 thiazine Methylene blue OBNB/OCNB 0,2 dark blue dark violet C.I. Basic blue 9 3 : 1 0,05 dark blue blue C.I. No. 52015 0,005 green greenish formamide 0,2 dark blue dark blue 0,05 dark blue dark blue 0,005 blue blue lauryl 0,2 dark blue violet alcohol 0,05 dark blue violet 0,005 blue blue OCNB 0,05 deep blue violet 0,01 green/blue violt 125 thiazine Thionin (Lauth's OBNB/OCNB 0,2 *dark red greenish violet violet) 3 : 1 0,05 dark red greenish 0,01 red pink 0,005 red beige formamide 0,2 violet-blue dark violet 0,05 violet-blue blue 0,005 violet lauryl 0,2 dark violet violet alcohol 0,05 violet violet 0,005 pink-violet violet OCNB 0,05 deep red violet 0,01 wine red pink 126 thiazine Toluidine blue O OBNB/OCNB 0,2 dark blue bluish violet C.I. Basic blue 17 3 : 1 0,05 dark blue violet C.I.No. 52040 0,005 greenish blue pink *not completely dissolved TABLE I Cont'd....

Concentration Colour No. Class Dye Solvent % (m/m) liquid solid OCNB 0,05 deep blue violet 0,01 blue/green pink/violet t.butanol 0,01 blue blue formamide 0,2 dark blue blue violet 0,05 dark blue dark blue 0,005 blue blue lauryl 0,2 dark blue violet alcohol 0,05 blue violet 0,005 light blue nearly colourless naphthalene 0,05 deep blue blue 127 thiazine Methylene green OBNB/OCNB 0,05 dark bluish green dark gree C.I. Basic green 5 3 : 1 C.I. No. 52020 formamide 0,05 dark bluish green dark bluish green lauryl 0,05 *blue grey alcohol 128 thiazine Azure A,B,C, OBNB/OCNB 0,05 *blue violet C.I. No. 52010 3 : 1 formamide 0,05 dark blue dark blue lauryl 0,05 *blue violet alcohol 129 thiazine Methylene violet OBNB/OCNB 0,05 dark violet dark violet C.I. No. 52041 3 : 1 *not completely dissovled TABLE I Cont'd..

Concentration Colour No. Class Dye Solvent % (m/m) liquid solid 130 amino- Murexide OBNB/OCNB 0,2 *brown yellow ketone C.I. No. 56085 3 : 1 0,05 brownish yellow yellow 0,05 yellow yellow 131 anthra- Savinyl green B OBNB/OCNB 0,2 dark green dark green quinone (Sandoz) 3 : 1 0,05 dark green green C.I. Solvent green 19 0,005 green light green formamide 0,2 *dark green dark green 0,05 *dark green green lauryl 0,2 dark bluish green green alcohol 0,05 bluish green green 0,005 green light green 132 anthra- Savinyl blus RS OBNB/OCNB 0,2 dark blue dark blue quinone (Sandoz) 3 : 1 0,05 dark blue blue C.I.Solvent blue 45 0,005 blue greenish blue formamide 0,2 *dark blue dark blue 0,05 *blue blue lauryl 0,2 dark blue dark blue alcohol 0,05 violet-blue blue 0,005 blue light blue 133 anthra- D + C green 6 OBNB/OCNB 0,2 dark green dark green quinone (American Cyanimid) 3 : 1 0,05 dark green green C.I. Solvent green 3 0,005 green green C.I. No. 61565 lauryl 0,2 dark greenish blue blue alcohol 0,05 greenish blue light greenish blue 0,005 greenish blue light greenish blue *not completely dissolved TABLE I C'ont'd..

Concentration Colour No. Class Dye Solvent % (m/m) liquid solid 134 anthra- Blue VIF Organol OBNB/OCNB 0,2 dark blue dark blue quinone (Ugine Kuhlmann) 3 : 1 0,05 dark blue blue C.I. Solvent blue 63 0,005 bluish green bluish green C.I. No. 61520 formamide 0,2 *dark blue blue 0,05 *blue blue lauryl 0,2 dark blue dark blue alcohol 0,05 dark blue blue 0,005 blue light blue 135 anthra- Alizarin OBNB/OCNB 0,2 darl yellow dark orange quinone C.I. Mordant red 11 3 : 1 0,05 dark yellow dark yellow C.I. No. 58000 0,005 yellow yellow lauryl 0,2 *brownish orange brownish orange alcohol naphthalene 0,05 yellow light orange 136 anthra- Alizaring cyanin 2R OBNB/OCNB 0,2 dark red dark brown quinone C.I. Mordant blue 50 3 : 1 0,05 dark red brown C.I.No. 58550 0,005 reddish pink yellow lauryl 0,2 dark red dark brown alcohol 0,05 dark red brown 0,005 purple pink naphthalene 0,m05 dark red dark red 137 anthra- Cellition blue extra OBNB/OCNB 0,2 dark blue dark green quinone C.I. Solvent blue 18 3 : 1 0,05 dark blue green Disperse blue 1 0,005 light green light green C.I. No. 64500 *not completely dissolved TABLE I Cont'd..

Concentration Colour No. Class Dye Solvent % (m/m) liquid solid lauryl 0,2 dark blue blue alcohol 0,05 vivid blue light blue 0,005 light blue light blue naphthalene 0,05 dark blue light blue 138 anthra- Alizarin blue S OBNB/OCNB 0,2 deep dark red black quinone C.I. Mordant blue 27 3 : 1 0,05 dark red greyish green C.I. No. 67415 0,005 dark orange light green lauryl 0,2 dark purple-red dark grey alcohol 0,05 red purple light purple 0,005 light blue colourless naphthalene 0,005 dark red grey 139 anthra- Nitrofast green GSB OBNB/OCNB 0,2 dark green dark green quinone C.I. Solvent green 3 3 : 1 0,05 dark green dark green C.I. No. 61565 0,005 greenish blue light green lauryl 0,2 deep dark blue deep dark blue alcohol 0,05 dark blue blue 0,005 blue light blue 140 anthra- Alizarin red S OBNB/OCNB 0,2 dark orange yellowish orange quinone C.I. Mordant red 3 3 :P 1 0,05 dark yellow dark yellow C.I. No. 58005 0,005 yellow yellow lauryl 0,2 dark orange-yellow dark yelloq alcohol 0,05 yellow light yellow 0,005 light pink colourless *not completely dissolved TABLE I Cont'd Concentration Colour No. Class Dye Solvent % (m/m) liquid solid 141 anthra- Chinalizarin OBNB/OCNB 0,2 red red quinone C.In. Mordant violet 26 3 : 1 0,05 orange-red reddish orange C.I. No. 58500 0,005 reddish orange dark yellow lauryl 0,2 *vermilion red alcohol 0,05 reddish orange reddish pink 0,005 pinkish orange pink 142 anthra- Oil blue N OBNB/OCNB 0,2 deep blue deep green quinone C.I. Solvent blue 14 3 : 1 0,05 deep blue moss green C.I. No. 61555 0,005 greenish blue bluish green 143 anthra- Solway purple OBNB/OCNB 0,2 deep blue deep blue quinone C.I. Acid violet 431 3 : 1 0,05 deep blue bluish green C.I.No 60730 0,005 light green light green 144 anthra- Purpurin OBNB/OCNB 0,2 *orange orange-red quinone C.I. No. 58205 3 : 1 0,05 orange reddish orange 0,005 light orange yellowish orange formamide 0,2 *dark red dark red 0,05 dark red dark red 0,005 red red lauryl 0,2 *orange orange alcohol 0,05 orange light orange 0,005 light orange light orange *not completely dissolved TABLE I Cont'd..

Concentration Colour No. Class Dye Solvent % (m/m) liquid solid 145 indigo Indigo Synthetic OBNB/OCNB 0.05 dark blue grey blue C.I. Vat blue 1 3 : 1 C.I. No 73000 lauryl 0.05 blue light blue alcohol 146 indigo Cromophtal Bordeaux OBNB/OCNB 0.2 brown reddish brown RS (Ciba - Geigy) 3 : 1 0.05 beige beige-yellow C.I. Pigment red 88 0,005 yellow yellow C.I. No. 73312 147 indigo Thioindigo red OBNB/OCNB 0,2 dark purple-red dark purple C.I. Vat red 41 3 : 1 0,05 carmine beige C.I. No 73300 0,005 yellowish orange yellow lauryl 0,2 dark red dark purple alcohol 0,05 purple light purple 0,005 light violet light violet 148 indigo Ciba blue OBNB/OCNB 0,2 deep blue green C.I. Vat blue 5 3 : 1 0,05 bluish green light green C.I. No. 73065 0,005 green greenish yellow 149 indigo Indigo carmine OBNB/OCNB 0,05 *yellowish green yellowish green C.I. Acid blue 74 3 : 1 C.I.No. 73015 150 phthalo- Savinyl blue GLS OBNB/OCNB 0,05 bluish green greenish blue cyanine (Sandoz) 3 : 1 C.I. Solvent blue 44 151 phthalo- Irgalith blue GLSM OBNB/OCNB 0,05 greenish blue blue cyanine (Ciba - Geigy) 3 : 1 C.I. Pigment blue 15:3 C.I. No. 74160 *not completely dissolved TABLE I Cont'd....

Concentration Colour No. Class Dye Solvent % (m/m) liquid solid 152 phthalo- Phathalocyanine OBNB/OCNB 0,05 dark green dar grey green cyanine C.I. Pigment blue 15 3 : 1 C.I. No. 74160 153 natural Alcannin OBNB/OCNB 0,2 red dark red C.I. Natural red 20 3 : 1 0,05 red purple-red C.I. No. 75530 0,005 red beige lauryl 0,2 brownish red light pink alcohol 154 natural Curcumin OBNB/OCNB 0,2 dark yellow dark yellow C.I. Natural yellow 3 3 : 1 0,05 yellow yellow C.I. No. 75300 0,005 yellow yellow 155 natural Quercitrindihydrate OBNB/OCNB 0,2 yellow yellow C.I. Natural yellow 10 3 : 1 0,05 yellow yellow C.I. No. 75720 0,005 yellow yellow 156 inorganic Prussian blue OBNB/OCNB 0,2 *green green pigments C.I. Pigment blue 27 3 : 1 0,05 light green light green C.I.No. 77510 0,005 yellowish green yellowish green *not completely dissolved Example VIII This Example gives combinations tested for colour change in various solvents and at different concentrations. Thess combinations include: (a) mixtures of compounds (1) above.

(b) mixtures of acids having a pK less than about from and basic dyes or basic indicators, (c) mixtures of organic acids having a pK less than about two and acidic dyes or acidic indicators, (d) mixtures of compounds (1) above and organic acidic compounds with a pK less than about 4, (e) mixtures of compounds (1) above and basic dyes or basic indicators, (f) mixtures of a dye having a molecular structure containing a lactone group and acids.

The results are given in Table II.

TABLE II No. Organic Compounds Total concen- Solvent Colour tration % m/m liquid solid 1 Quinaldine red/ 0,05 OCNB wine orange acridine orange 1:1 2 Toluidine blue O/ 0,05 OCNB green brown acridine orange 1:1 3 Same mixture 0,05 OCNB/OBNB green brownish 1 : 3 yellow 4 Same mixture 0,05 t. butanol green brownish yellow 5 Same mixture 0,05 sym.

trioxane* green brown 6 Acridine orange/ 0,015 OCNB red reddishfuchsin 2:1 orange 7 Bromophenol blue/ 0,05 OCNB/OBNB bue greenish pinacyanol iodide 1 : 3 yellow 8 Chlorophenol red/ 0,05 OCNB/OBNB greenish light pinacyanol iodide 1 : 3 blue yellowish brown 9 Chlorophenol blue/ 0,05 OCNB/OBNB blue green pinacyanol iodide 1 : 3 10 Chlorocresol green/ 0,05 OCNB/OBNB blue moss green pinacyanol iodide 1 : 3 11 Phthalocyanine/ 0,05 OCNB/OEBNB blue brown pinacyanol iodide 1 : 3 12 Bromochlorophenol blue/ 0,05 OCNB/OBNB greenish yellowish pinacyanol chloride 5:1 1 : 3 blue green TABLE II Cont'd..

13 Bromocresol purple/ 0,05 OCNB/OBNB red orange 2-(p-dimethylaminostyryl) 1 : 3 orange -1-ethyl-pyridinium iodide 14 Bromochlorophenol blue/ 0,05 OCNB/OBNB red yellow 2-(p-dimethylaminostyryl) 1 : 3 orange -1-ethyl-pyridinium iodide 15 Bromophenol red/ 0,05 OCNB/OBNB red orange 2-(p-dimethylaminostyryl) 1 : 3 orange -1-ethyl-pyridinium iodide 16 Chlorocresol green/ 0,05 OCNB/OBNB red yellow 2-(p-dimethylaminostyryl) 1 : 1 orange -1-ethyl-pyridinium iodide *trimer of formaldehyde rations are mass rations TABLE II Cont'd..

No. Organic Compounds Total concen Solvent Colour tration % m/m liquid solid 17 Bromophenol blue/ 0,05 OCNB/OBNB blue green crystal violet 1:3 18 Chlorophenol red/ 0,05 OCNB/OBNB green red cryptocyanine 1:3 19 Bromochlorophenol blue/ 0,05 OCNB/OBNB green yellow cryptocyanine 1:3 20 Chlorophenol red/ 0,05 OCNB/OBNB green red dicyanine A 1:3 21 Bromochlorophenol blue/ 0,05 OCNB/OBNB green yellow dicyanine A 1:3 22 Bromocresol purple/ 0,05 OCNB/OBNB greenish green 1:3 blue 3,3'-diethylthiadicarbocyanine iodide 23 Bromophenol blue/ 0,05 OCNB/OBNB greenish yellow 3,3'-diethylthiadicarbo- 1:3 blue green cyanine iodide 24 Bromochlorophenol blue/ 0,05 OCNB/OBNB red yellow 1,1'-diethyl-2,2'-cyanine 1:3 orange iodide 25 Chlorophenol red/ 0,05 OCNB/OBNB green red phthalocyanine 1:3 26 Bromophenol blue/ 0,05 OCNB/OBNB red yellow ethyl red 1:3 TABLE II Cont'd..

27 Chlorophenol blue/ 0,05 OCNB/OBNB red yellow ethyl red 1:3 28 Chlorophenol red 0,05 OCNB/OBNB red orange ethyl red 3:1 1:3 29 Bromocresol purple/ 0,05 OCNB/OBNB red yellow ethyl red 1;3 30 Bromochlorophenol blue/ 0,05 OCNB OBNB purple yellow ethyl red 1:3 red 31 Bromophenol red 0,05 OCNB OBNB reddish violet ethyl red 3:1 1:3 violet 32 Bromochlorophenol blue/ 0,05 OCNB/OBNB dark yellow ethyl red/pinacyanol 1:3 blue iodide 33 Murexide/quinaldine red 0,05 OCNB/OBNB purple light 1:3 brownish yellow 34 Bromochlorophenol blue/ 0,05 OCNB/OBNB purple yellow Quinaldine red/pinacyanol 1:3 iodide ratios are mass ratios TABLE II Cont'd.

No. Organic Compounds Total concen- Solvent Colour tration % m/m liquid solid 35 Phthalocyanine/ 0,05 OCNB/OBNB violet dark quinaldine red 1:3 brown 36 Fluorescein/pinacyanol 0,05 OCNB/OBNB blue brownish iodide 1:3 purple 37 trichloroacetic acid/ 0,05 OCNB/OBNB green yellow cryptocyanine 1:3 38 Maleic acid*/crypto- 0,05 OCNB/OBNB green light cyanine 1:3 yellow green 39 Maleic acid/dicyanine A 0,05 OCNB/OBNB green light 1:3 yellow green 40 Naphthalenesulphonic acid/ 0,05 OCNB/OBNB greenish yellow dicyanine A 1:3 yellow 41 Trichloroacetic acid/ 0,05 OCNB/OBNB greenish yellow dicyanine A 1:3 yellow 42 3,4,5,6-tetrabromophenol- 0,05 OCNB/OBNB red orange sulphonephthalein/ 1:3 orange 2-(p-dimethylaminostyryl) -1-ethyl-pyridinium iodide 43 Thymolphthalein/ethyl red 0,05 OCNB/OBNB red purple 1:3 44 3,4,5,6-tetrabromophenol- 0,05 OCNB/OBNB red brownish sulphonephthalein/ethyl red 1::3 red 45 Naphthalenesulphonic acid/ 0,05 OCNB/OBNB red yellow ethyl red 1:3 TABLE II Cont'd...

46 2,4-dinitrobenzenesulphonic 0,30 OCNB red yellow acid/ethyl red 5:1 47 Naphthalenesulphonic acid 0,05 OCNB/OBNB purple yellow quinaldine red 1:3 red 48 Trichloroacetic acid/ 0,05 OCNB/OBNB purple yellow quinaldine red 1:3 49 2,4-dinitrobenzenesulphonic 0.30 OCNB red yellow acid/quinaldine red 5 : 1 50 3,4,5,6-tetrabromophenol- 0,05 OCNB/OBNB reddish yellow sulphonephthalein/quinaldine 1:3 pink red 51 Naphthalenesulphonic acid/ 0,50 OCNB/OBNB red yellow 1,1'-diethyl-2,2'-cyanine 1:3 iodide *Maleic acid is poorly soluble in the solvents ratios are mass ratios TABLE II Cont'd..

No. Organic Compounds Total concen- Solvent Colour tration % m/m liquid solid 52 trichloroacetic acid/ 0,05 OCNB/OBNB red yellow 1,1'-diethyl-2,2'- 1:3 cyanine iodide 53 maleic acid*/1,1'-diethyl 0,05 OCNB/OBNB red yellow -2,2'-cyanine iodide 1:3 54 trichloroacetic acid/ 0,05 OCNB/OBNB blue light 3,3'-diethylthiadicarbo- 1:3 green rose cyanine iodide 55 Naphthalenesulphonic 0,05 OCNB/OBNB green yellow acid/crystal violet 1:3 brown 56 Maleic acid*/crystal 0,05 OCNB/OBNB blue green violet 1:3 57 Dichloroacetic acid 0,05 OCNB/OBNB blue green crystal violet 1:1 1:3 58 Dichloroacetic acid/ 0.20 OCNB/OBNB blue dark crystal violet 3:1 1:3 green 59 Naphthalenesulphonic 0,05 OCNB/OBNB green yellow acid/ethyl violet 1:3 60 Trichloroacetic acid/ 0,05 OCNB/OBNB green yellow ethyl violet 1:3 61 Maleic acid*/ethyl violet 0,05 OCNB/OBNB blue yellowish 1::3 green 62 Naphthalenesulphonic acid 0,05 OCNB/OBNB purple yellow basic fuchsin 1:3 TABLE II Cont'd..

63 Naphthalenesulphonic acid/ 0,05 OCNB purple greenish basic fuchsin 4:1 64 Maleic acid/basic fuchsin 0,05 OCNB/OBNB red blue 1:3 violet 65 Chloroanilic acid/basic 0,05 OCNB/OBNB red grey fuchsin 1:3 66 Bromophenol blue/basic 0,05 OCNB/OBNB red moss fuchsin 1:3 green 67 Bromophenol red/brilliant 0,05 OCNB/OBNB green dark green 1:3 green 68 Bromochlorophenol blue/ 0,05 OCNB/OBNB blue green brilliant green 1;3 69 Bromochlorophenol blue/ 0,05 OCNB/OBNB blue light ethyl violet 1:3 moss green *Maleic acid is poorly soluble in the solvents ratios are mass ratios TABLE II Cont'd..

No. Organic Compounds Total concen- Solvent Colour tration % m/m liquid solid 70 Cryptocyanine/5-(p- 0,05 OCNB/OBNB dark dar dimethylaminobenzili- 1:3 yellow brown dene/rhodanine 71 Dicyanin A/ 0,05 OCNB/OBNB green purple 5-(p-dimethylamino- 1:3 brown benzilidene) rhodanine 72 Sodium phthalocyanine/ 0,05 OCNB/OBNB blue brown pinacyanol iodide 1:3 73 Sodium phthalocyanine/ 0,05 OCNB/OBNB violet light quinaldine red 1:3 brown 74 Sodium phthalocyanine/ 0,05 OCNB/OBNB green red chlorophenol red 1:3 75 Naphthalenesulphonic acid/ 0,05 OCNB/OBNB yellow very bromochlorophenol blue 1:3 light red 76 Naphthalenesulphonic acid/ 0,05 OCNB/OBNB orange red chlorophenol blue TABLE II Cont'd..

77 Naphthalenesulphonic acid/ 0,05 OCNB/OBNB orange red bromocresol purple 1:3 78 Crystal violet lactone/ 0,10 OCNB/OBNB yellow blue phenol 1:1 79 Crystal violet lactone/ 0,05 OCNB/OBNB yellowish blue bisphenol A 1 : 1 1:3 green 80 Crystal violet lactone/ 0,05 OCNB/OBNB green green benzoic acid 1:1 1:3 81 Crystal violet lactone/ 0,05 OCNB/OBNB yellowish greenish 3-nitrophenol 1:1 1:3 green blue 82 Crystal violet lactone/ 0,05 OCNB/OBNB yellowish blue pyrocatechol 1:1 1:3 green rations are mass rations Example IX This Example demonstrates the use of insoluble nucleating agents in a temperature indicating device in order to render the composition of matter recrystallizable at a predetermined temperature.

A Number of cavities formed in an aluminium carrier layer were filled with a mixture of ortho-bromonitrobenzene and ortho-chloronitrobenzene (mass ratio 3:1), containing 0.025 mass % of pinacyanol iodide to which different amounts of nucleating agents had been added. The cavities thus filled were provided with a heat-sensitive transparent Surlyn 1652 film (Registered Trade Mark of E.I.Du Pont de Nemours & Company, U.S.A.) laminated to a polyester film (Melinex I.C.I. - Registered Trade Mark).

After recrystallization of the chemicals at -400C, the indicating device was heated for one hour at about 55"C (imitation of storage at high temperatures).

Then the indicating device was cooled at -6 C and the percentage of cavities in which the mixture has recrystallized was determined.

In a second series the indicating device containing recrystallized mixtures, was heated in a water bath for 45 seconds just above the melting point of the chemicals (about 38"C) in order to imitate a measurement of the temperature of the human body. Then the indicating device was cooled to room temperature and the percentage of cavities in which the chemicals had crystallized was determined.

In all about 170 cavities were filled for each nucleating agent investigated.

For comparison, cavities were filled with the same OBNB/OCNB mixture containing 0.025 mass % pinacyanol iodide but without nucleating agents.

The results are presented in Table III.

It appears that whereas the addition of a nucleating agent favourably influences the recrystallization at -60C, it does not affect the undercooling at room temperature. nucleating agent particle concentration % recrystallized after cooling to size ( m) % (m/m) room temperature for 15 min. -6 C (cooling time) (after heating to 38 C) (after heating to 55 C) Aerosil 380 10 0.1 6 86 (10 min) Lichrosorb RP8 (Registered Trade Mark) (Merck, Germany) chemically modified silica 5 0.1 < 1 95 (10 min) 399 magnesium silicate 5 0.1 0 100 (10 min) (Talc IT extra 5 micron) (Elvers Netherlands) 1 9 100 (10 min) Talc Mistron Super Frost 0.1 1 100 (10 min) (Cyprus Ind.Minerals Corp.) 2 1 < 1 100 ( &num; ) 2.5 0 100 ( " ) 5 3 100 ( &num; ) Boron, amorph 0.05 0.1 3 93 (40 min) (Starck, Germany) Titanium carbide 0.05 0.1 2 100 (20 min (Starck, Germany) Diamond 2-4 0.1 < 1 95 (20 min) Spring A.G., Switserland Boron, crystalline 0.05 0.1 < 1 98 (20 min) (Starck, Germany) Molybdenium disulphide abt. 10 0.1 1 95 (10 min) Fluka AG, Switserland Alumina (Tonerde) 0.25 0.1 0 100 (10 min) Dujardin, Germany Porous alumina 5 0.1 0 100 (20 min) (Lichrosorb Alox T) Merck, Germany 30 (10 min) - - 2 none 46 (60 min) Example X This Example demonstrates the use of a pretreated aluminium carrier layer for rendering the composition of matter recrystalizable at a predetermined temperature.An aluminium carrier layer provided with cavities was passivated by cleaning the aluminium with acetone, pickling in a 2% solution of sodium hydroxide, subsequent pickling in 10% nitric acid and immusion in boiling water for 5 mmutes. The cavities were filled with a mixture of ortho-chloronitrobenzene and ortho-bromonitrobenzene (mass ratio 1:3) containing 0.025 mass % of pinacyanol iodide. The filled cavities were further treated as described in Example IX.

For comparison, cavities formed in untreated aluminium were filled with the abovementioned mixture and treated in a similar way.

The results are given in Table IV, TABLE IV Treatment % recrystallized after cooling to room temperature for 15 -6" (cooling time) min (after heating to (after heating to 38"C) 55"C) none 2 30 10 min) 46 (60 min) passivation about 5 100 (30 min) It appears that the passivation of the aluminium carrier layer favourably influences recrystallization at -6 C.

Example XI A transparent polyester film (Melinex, supplied by I.C.I.) provided with an adhesive layer of polyisobutylene is pressed together with an aluminium layer foil. As a measure of the adhesive strength is taken the force in g/cm which is required to peel the polyester film off the aluminium foil at a rate of 30 cm/minute. This force should be at least about 150 g/cm. The influence on the magnitude of the peeling force has been investigated of the nature of the aluminium surface (rough, smooth, etched), the ty e of polyisobutylene (molecular weight, mixture) and bonding pressure (5 and 50 kg/cm . The polysobutylene types used have been obtained from BASF, Ludwigshafen, W-Germany and are marketed under the trade name Oppanol (Registered Trade Mark). The results are listed in Table V.

TABLE V Peeling force in g/cm Pretreatment of PIB1 PIB2 PIB3 PIB4 PIB5 aluminium foil A B A B A B A B A B rough surface 1) 550 600 400 600 100 150 20 20 400 450 smooth surface 600 600 600 600 150 200 100 130 400 450 etched: 2) rough surface 600 600 600 600 100 240 40 120 - smooth surface 600 600 600 600 250 330 200 300 - coated: 3) rough surface 400 400 400 400 400 400 400 400 - smooth surface 300 300 300 300 300 300 300 300 - A = used bonding force 5 kg/cm2 B = used bonding force 50 kg/cm2 1) rough surface: mechanically roughened 2) etched: pretreatment with a solution of sodium metasilicate in water 3) coated: surface layer Oppanol B 150, thickness 5 y.

PIB1: Oppanol B15, average mol.wt. 77-92.103 PIB2: Oppanol D3061, average mol.wt. about 140.103 PIB3: Oppanol B50, average mol.wt. 340-480.103 PIB4: Oppanol B150, average mol.wt. 2.3-3.3.106 PIB5: mixture of Oppanol B15/B150 (1:1) Example XII Of polyisobutylene the permeability is investigated for the chemicals used in the temperature indicating device. Polyisobutylene films are formed from a solution disposed on paper. The films thus obtained are made into bags of about 60 cm2 which are filled with 2.5 grammes of a mixture of ortho-chloronitrobenzene and ortho-bromonitrobenzene (weight ratio 62:38) and sealed. After being weighed, the bags are stored at 320C in a room with air circulation and after different periods the loss of weight is determined. The results are summarized in Table VI.

TABLE VI Sample Loss of weight in mg/hl/cm2 PIB1 0.12 PIB2 0.14 PIB3 0.17 Surlyn 1652 (control) 1.05 The designations PIB1, PIB2 and PIB3 have the same meaning as in Example XI. For comparison also mention is made of the result obtained with a film (thickness about 45 ,u) of an ionomeric adhesive Surlyn 1652. It appears that the polyisobutylene samples are far less permeable than the ionomeric adhesive.

Example XIII Cavities formed in an aluminium carrier layer are filled with mixtures of orthochloronitrobenzene and ortho-bromonitrobenzene and sealed with a cover layer of polyester film provided with a polyisobutylene adhesive layer. The test objects thus obtained are stored at 200C and 32"C and examined under a stereo microscope to establish whether the chemicals dissolve in the adhesive layer, disappear from their cavities or become liquid.

Observations were taken for 40 days. The results are given in Table VII.

TABLE VII Sample Observations PIB1 After a few days viscous deformation of the glue layer occurs at 200C.

No leaking away or dissolving of the chemicals after 40 days at 32"C.

PIB2 ditto PIB3 After a few days slight viscous deformation of the polyisobutylene occurs at 20"C. At the end of the observation period some leaking away of chemicals as a result of the polyisobutylene becoming detached from the aluminium.

P1B4 After 40 days at 320C no viscous deformation occurs. No leaking away or dissolving of chemicals in those places where the adhesion between aluminium and polyisobutylene has been maintained. In a few places the polyisobutylene layer has become detached from the aluminium and chemicals have leaked away there.

From this table it appears that the chemicals neither leak away nor dissolve, provided that the adhesion to the aluminium foil is kept up.

High-molecular weight polyisobutylene (PIB4) is the least liable to viscous deformation.

Example XIV In this example the reproducibility of the temperature indication is demonstrated. A number of cavities formed in an aluminium carrier layer are filled with a series of mixtures of ortho-chloronitrobenzene, ortho-bromonitrobenzene and 0.1% by weight of orasol blue BLN (solvent blue 49), whose melting temperatures progressively increase by 0.1"C. The cavities thus filled are covered with Whatman (Registered Trade Mark) chromatography paper No. 1 and subsequently sealed with a polyester film (Melinex) provided with a pressure-sensitive adhesive layer of polyisobutylene. The polyisobutylene used is a mixture of equal parts of Oppanol B15 (average molecular weight 77,000-92,000) and Oppanol B100 (average molecular weight 1.08-1.46x106). The test objects are stored at 28"C and after 3,7 and 10 weeks, respectively, placed in a water bath of a particular temperature to measure the temperature at which discoloration of the indicator layer takes place. The results obtained as average values of the 4 temperature indicating devices are listed in Table VIII.

TABLE VIII Temperature at which discoloration occurs ( C) after 0 weeks 36.40 3 weeks 36.45 7 weeks 36.48 10 weeks 36.50 It appears that the temperature indication as a function of time does not or hardly undergo any change.

Example XV(comparative) A numer of known adhesives with which an adhesive layer can be formed at room temperature are examined in the way described in Example XIII. The aluminium foil used has previously been etched. From the results summarized in Table IX it appears that of the adhesives examined, which all fall beyond the scope of the present invention, none are suitable to be used for the present purpose envisaged.

TABLE IX Adhesive Solvent Cover Curing or Observations layer drying time (min) Expoxide none polyester 3-14 influence of curing time: coating 3-6 min.: chemicals turn liquid thickness 10 3-14 min.: poor adhesion to aluminium Ceta Bever 3-13 min.: after 2 days at 32 C chemicals have disappeared (dissolved in adhesive layer) Epoxide none polyester 5-45 influence of curing time: coating 5-25 min.: chemicals turn liquid thickness 10 25-35 min.: after 4 days at 20 C yellowing Araldite and disappearing of chemicals Ciba-Geigy bi-component methyl- polyester solvent influence of drying time: polyurethane ethyl evaporated 2.5-4.5 hours: after 4 days at 32 C Adcote 301A/350 ketone at 50 C chemicals disappear Morton-Williams > 4.5 hours: poor adhesion to PUR 2837 aluminium Ciba-Geigy Silicone RTV 108 none cellophane 0-45 0-30 min: chemicals turn liquid General Electric 45 min.: poor adhesion to aluminium is affected 30-45 min.: after 7 days at 20 C chemicals by moisture disappear Silgrip 574 none polyester none after 3 days at 20 C: chemicals turn liquid General Electric and dissolve in the glue layer pressure-senisitive glue (silicones) polyvinyl alcohol water cellophane solvent after the water had been entirely removed, Elvanol 71-30 evaporated adhesion between polyvinyl alcohol and Du Pont at 20 C aluminium was insufficient with all samples ELVANOL, ADCOTE and ARALDITE are Registered Trade Marks

Claims

WHAT WE CLAIM IS:

1. A composition consisting essentially of at least: (1) a solvent comprising a single substance or a mixture of substances and adapted to change at substantially a predetermined temperature from a solid phase to a liquid phase and (2) an indicator system comprising one or more substances different from the solvent, the indicator system being soluble in the solvent when the latter is in the liquid phase, and reversibly changing its colour as visible to the naked eye when the solvent passes from the solid to the liquid phase and from the liquid to the solid phase.

2. A compositin as claimed in claim 1 wherein the solubility of the indicator system in the solvent, when the latter is in the solid phase, is so much lower than the solubility of the indicator in the solvent, when the latter is in the liquid phase, that the indicator is partly or entirely separated when the solvent passes from the liquid to the solid phase.

3. A composition as claimed in claim 1 or claim 2 consisting essentially of: (A) a solvent adapted to change at a predetermined temperature from a solid phase to a liquid phase, and (B) an indicator comprising one or more suitable organic compounds soluble in the solvent in the liquid state and adapted to change the colour of the composition visible to the naked eye upon the change of state of the solvent at substantially the predetermined temperature, which indicator is selected from (1) a group of single compounds which are monoazo, disazo, triaryl-methane, xanthene, sulphonephthalein, acridine, quinoline, azine, oxazine, thiazine, anthraquinone or indigoid compounds, and the individual compounds:Aurantia, Orasol orange RLN, Diamin green B, Direct green G, Fast red salt 3 GL, Fast blue salt BB, Fast garnet salt GBC, Carta yellow G 180%, Murexide, savinyl blue GLS, Iragalith blue GLSM, Phthalocyanine and Alcannin.

2 mixtures of a one or more organic acid compounds, having a pK of less than four, and (b) one or more basic dyes or basic indicators.

(3) mixtures of (a) one or more organic acids having a pK of less than 2 and (b) one or more acid dyes or acidic indicators, (4) mixtures of (4) mixtures of dyes or acidic indicators, (a) one or more organic acid compounds having a pK of less than 4 and (b) one or more of the compounds (1) above, 5 mixtures of a one or more basic dyes or basic indicators and (b) one or the more compounds (1) above, (6) mixtures of (a) one or more dyes having a molecular structure containing lactone group, and (b) one or more acids having a pK in the range of from 8 to 12.

4. A composition as claimed in claim 3 wherein the monazo compound is 4-(pethoxyphenylazo)-m-phenylenediamine mono-hydrochloride, Orasol navy blue, Organol orange, Janus green, Irgalith red, P4R, Dimethyl yellow, Fast yellow, Methyl red, sodium salt, Alizarin yellow R, Eriochrome black T, Chromotrope 2R, Ponceau 6R, Yellow Orange S, Brilliant Ponceau 5R, Chrysoidin G, Erichrome black A, Benzyl orange, Ponceau G/R/2R or Chromolan yellow.

5. A composition as claimed in claim 3 wherein the disazo dye is: Fat red BS, Sudan red B, Bismarck brown G, Fat black, Resorcin brown, Benzofast pink 2 BL or Oil red EGN.

6. A composition as claimed in claim 3 wherein the triarylmethane dye is: methyl violet, Xylene cyanol FF, Erioglaucine, Fuchsin NB, Fuchsin, Parafuchsin, Aurintricarboxylic acid ammonium salt, Patent blue, Victoria blue R, Crystal violet or Irgalith blue TNC.

7. A composition as claimed in claim 3 wherein the xanthene dye is: Phloxin B, Fluorescein sodium salt, Rhodamine B, Rhodamine B base, Rhodamine 6 G, Pyronin G, Irgalith Magenta TCB, Irgalith pink TYNC, Eosin Scarlet, Eosin yellowish,Erythrosin extra bluish, 45'-Dibromofluorescein, Ethyleosin, Gallein, Phloxine, Erythrosin yellowish blend or Cyanosin B.

8. A composition as claimed in claim 3 wherein the sulphonephthalein dye is: Cresol red, Chlorophenol red, Chlorophenol blue, Bromophenol blue, Bromocresol purple or Chloro-cresol green.

9. A composition as claimed in claim 3 wherein the acridine dye is Coriphosphine 0, Acriflavine or Acridine orange.

10 A composition as claimed in claim 3 wherein the quinoline dye is: Pinacyanol chloride, Pinacyanol bromide, Pinacyanol iodide, Quinaldine red, Cryptocyanine, 1,1'- Diethyl-2,2'-cyanine iodide, 2-(p-Dimethylaminostyryl)-l-ethyl-,pyridinium iodide, 3,3' Diethylthiadicarbocyanine iodide, Ethyl red, Dicyanine A, Merocyanine 540 or Neocyanine.

11. A composition as claimed in claim 3 wherein the azine dye is: Neutral red chloride, Neutral red iodide, Nigrosine, Savinyl blue B, Orasol blue BLN, Safranin 0, Azocarmin G, Phenosafranine, Azocarmine BX or Rhoduline violet.

12. A composition as claimed in claim 3 wherein the oxazine dye is: Solophenyl brilliant blue BL, Nile blue A Gallocyanine Gallamine blue or Celestine blue.

13. A composition as claimed in claim 3 wherein the thiazine dye is: Methylene blue, Thionin, Toluidine blue 0, Methylene green or Azure A/B/C.

14. A composition as claimed in claim 3 wherein the anthraquinone dye is: Savinyl green B, Savinyl blue RS, D+C green 6, Blue VIF Organol, Alizarin, Alizarincyanin 2R, Celliton blue extra Alizarin blue S, Nitro fast green GSB, Alizarin red S, Chinalizarin, Oil blue N, Solway purple or Purpurin.

15. A composition as claimed in claim 3 wherein the indigoid dye is: Ciba blue, Indigo synthetic, Cromophtal Bordeaux RS or Thioindigo red.

16. A composition as claimed in claim 3 in which the organic acid compounds having a pK of less than four are halogenated sulphonephthaleins and the basic dyes or basic indicators are the aminotriphenyl methanes and/or their soluble salts, 8-hydroxyquinoline or the cyanines, with the proviso that if the basic compound consists solely of one or more aminotriphenyl methanes or their soluble salts the acid compounds must be a tetrahalogenated sulphonephthaleins or an organic acid having a pK of less than 2.

17. A composition as claimed in claim 3 in which the acid dyes or acid indicators, in the mixture with one or more organic acids having a pK of less than 2, are halogenated sulphonephthaleins.

18. A composition as claimed in claim 3 in which the organic acid compound having a pK of less than 4 is oxalic acid, maleic acid, dichloroacetic acid, trichloroacetic acid, 2-naphthalenesulphonic acid, chloroanilic acid, bromophenol blue, bromothymol blue, chlorophenol red, bromochlorophenol blue, bromocresol green, 3,4,5,6 tetrabromophenolsulphonephthalein, bromophenol red, chlorocresol green, chlorophenol blue, bromocresol purple or 2,4-dinitrobenzenesulphonic acid.

19. A composition as claimed in claim 3 in which the basic dye or basic indicator is basic fuchsin, pinacyanol iodide, pinacyanol chloride, pinacyanol bromide, 2 p(dimethylaminostyryl)-l-ethyl-pyridinium iodide, crystal violet, crytocyanine, dicyanine A, 3,3'-diethylthiacarbocyanine iodide, 1,1 '-diethyl-2,2' -cyanine iodide, ethyl red, quinaldine red, ethyl violet, brilliant green, pararosaniline, pararosaniline acetate, 8hydroxyquinoline, l-ethylpyridinium iodide or 5-(p-dimethylaminobenzylidine)rhodanine.

20. A composition as claimed in claim 3 wherein the dye having a molecular structure containing a lactone group is crystalvioletlactone and the acid having a pK of 8 to 12 is 3-nitrophenol, bisphenol A, pyrocatechol or phenol.

21. A composition as claimed in claim 3 wherein the organic compound is pinacyanol iodide.

22. A composition as claimed in claim 3 wherein the organic compound is chlorophenol red.

23. A composition as claimed in claim 3 wherein the organic compound is alizarin blue S.

24. A composition as claimed in claim 3 wherein the organic compounds are bromophenol blue and basic fuchsin.

25. A composition as claimed in claim 3 wherein the organic compounds are chlorophenol blue and ethyl red.

26. A composition as claimed in claim 3 wherein the organic compounds are trichloroacetic acid and 3,3'-diethylthiadicarbocyanine iodide.

27. A composition as claimed in any one of claims 3 to 26 wherein the weight percentage of organic compounds soluble in the solvent is from 0.005 to 0.2% of the weight of the solvent and the soluble organic compounds.

28. A composition as claimed in any one of claims 3 to 27 wherein the predetermined temperature is from 35"C to 42"C.

29. A composition as claimed in any one of claims 3 to 28 wherein the solvent is ortho-chloronitrobenzene, ortho-bromonitrobenzene, l-thymol, 2-naphtol, 2ethoxybenzamide, naphthalene, para-dichlorobenzene, ortho-iodonitrobenzene, metaiodonitrobenzene, para-iodonitrobenzene, para-chloronitrobenzene, metabromonitrobenzene, para-bromonitrobenzene, para-dibromonitrobenzene, para-toluic acid, n.tetracosane, l-tetradecanol, stearic acid, t.butanol, laurylalcohol, formamide, paraffin, dioxane, symmetric trioxane, indole, dibenzofurane, or water.

30. A composition as claimed in any one of claims 3 to 29 wherein the solvent is a binary mixture of ortho-chloronitrobenzene and ortho-bromonitro-benzene.

31. A composition as claimed in any one of claims 1 to 30 wherein the composition contains impurities of less than 0.3% thereby rendering the composition capable of undercooling.

32. A composition as claimed in any one of claims 1 to 30 containing an amount of 0.001 to 10.0% by weight of a soluble or a non-soluble nucleating agent, thereby rendering the compositions capable of recrystallisation at a substantially predetermined temperature.

33. A composition as claimed in claim 32 wherein the nucleating agent is anthra uinone, talc, aluminium oxide, silicon dioxide, modified-silica, boron, titanium carbide, diamond or molybdenium disulfide.

34. A composition as claimed in claim 33 wherein the nucleating agent is talc having a particle size in the range of from 0.1 to 10 micrometers.

35. A composition as claimed in claim 1 substantially as hereinbefore described with reference to any one of Examples I to V and VII to XIV.

36. A temperature-indicating device comprising a heat-conducting carrier and a transparent cover sheet means in sealing engagement with the carrier, the carrier having or or more spaced regions defined therein for the determination of a like number of predetermined temperatures in a predetermined temperature range, with a like number of different compositions -contained therein, and with a single composition being deposited in each of the regions and being associated with a single one of the predetermined temperatures, the compositions used being the compositions as claimed in any one of claims 1 to 35.

37. A device as claimed in claim 36 wherein the regions are cavities in the heat-conducting carrier.

38. A device as claimed in claim 36 or claim 37 wherein the compositions are in an essentially linear melting point-to-composition relationship over the temperature range represented by the plurality of compositions.

39. A device as claimed in any one of claims 36 to 38 wherein the surface of the heat-conducting carrier means has been anodized or passivated.

40. A device as claimed in any one of claims 36 to 39 wherein the each of the compositions associated with a particular cavity fills that cavity except for a substantially spherical void within the cavity.

41. A device as claimed in any one of claims 36 to 40 wherein a layer of absorbent material is located between the cover-sheet and the composition.

42. A device as claimed in any one of claims 36 to 41 wherein the transparent cover sheet means and the heat-conducting carrier are sealed to each other by means of an adhesive layer of a pressure-sensitive adhesive which consists entirely or substantially of polyisobutylene.

43. A device as claimed in claim 42 wherein the average molecular weight of the polyisobutylene is in the range from 50,000 to 5,000,000.

44. A device as claimed in claim 43 wherein the average molecular weight of the polyisobutylene is in the range of from 450,000 to 4,000,000.

45. A device as claimed in claim 44 wherein the adhesive layer consists of a mixture of 30 to 70% by weight of polyisobutylene having an average molecular weight in the range of from 70,000 to 100,000 and 70 to 30% by weight of polyisobutylene having an average molecular weight in the range of from 1,000,000 to 3,500,000.

46. A device as claimed in claim 45 wherein the adhesive layer consists of substantially equal amounts by weight of polyisobutylene having an average molecular weight in the range of from 70,000 to 100,000 and polyisobutylene having an average molecular weight in the range of from 1,000,000 to 3,500,000.

47. A device as claimed in any one of claims 42 to 46 wherein the carrier layer is aluminium foil having an etched surface.

48. A device as claimed in any one of claims 42 to 47 wherein the carrier layer is aluminium foil having a polyisobutylene surface layer applied from a solution in an organic solvent.

49. A device as claimed in claim 48 wherein the polyisobutylene surface layer applied to the carrier layer has a thickness of from 2 to 10 micrometers.

50. A device as claimed in claim 48 or claim 49 wherein the surface layer applied to the carrier layer is polyisobutylene having an average molecular weight in the range of from 2,000,000 to 3,500,000.

51. A device as claimed in claim 50 wherein the carrier layer having a polyisobutylene surface layer is bonded to the transparent cover sheet by means of a pressure-sensitive adhesive layer of polyisobutylene having an average molecular weight in the range of from 2,000,000 to 3,500,000.

52. A temperature-indicating device which comprises a layer of absorbent material in which a composition as claimed in any one of claims 1 to 35 has been absorbed and two transparent cover sheets in sealing engagement with each other enclosing the absorbent material.

53. A device as claimed in claim 41 or claim 52 wherein the absorbent material is a hydrophobic synthetic paper.

54. A temperature indicating device as claimed in claim 36 substantially as hereinbefore described wit reference to and as illustrated in any one of Figures 1 to 14 of the accompanying drawings.

55. A method of determining a temperature to be measured which comprises using a temperature-indicating device as claimed in any one of claims 36 to 54.