DE1026556B - Process for the production of an active substance which responds to carbon monoxide as well as process and device for the display of carbon monoxide - Google Patents

Description

GERMAN

The invention relates to a method for producing a carbon oxide display composition, which in on is obtained in a known manner from a solution, the palladium chloride and a dye Group Alizarinsulfonate, in particular Alizarinrot S or Orthotolidin, contains and on an inorganic one Carrier, in particular silica gel, is applied.

According to the invention, the solution used to produce the carbon oxide display composition is additionally used Cuprous chloride and a second color, namely guinea green, were added. The cuprous chloride can contain an addition of sodium chloride or other chlorides.

It is known that carbon oxide display compositions made from palladium chloride and alizarine sulfonates or orthotolidine enable carbon oxide to be displayed relatively quickly. The mass is blackened by the presence of carbon monoxide. With the addition of cuprous chloride and guinea green as further components of the carbon oxide display compound, a compound is created which, after the effect of the carbon oxide has ceased, releases the carbon oxide again and thus takes on its original light color again. So the mass regenerates itself.

The mass according to the invention can be converted into a running one according to a special embodiment Use monitoring of the carbon oxide content of closed rooms and the like. You need to do this only to apply the mass to a transparent carrier and through this carrier a To let the light beam fall on a photocell, which then blackens the display strip of the Photocurrent is changed and a warning sign can be triggered as a result. If there is no or If the exposure to carbon dioxide decreases, the photocurrent decreases by lightening the display mass its normal position again, and the warning system is put out of operation again.

A purely visual observation can also be provided by drawing several strips on a map, which are adjusted to a different sensitivity, and depending on the number of blackened ones or discolored strips provide a reliable and quick conclusion as to the existing carbon oxide content can pull. For example, there are five different sensitivities of the display mass be provided in order to detect a carbon oxide range of 0 to 0.1% carbon oxide in air. For example in the following way:

1. from 0.002 to 0.01% CO

2. from 0.01 to 0.03% CO

3. from 0.03 to 0.05% CO

Method of manufacture
one responsive to carbon dioxide

Active ingredient as well as method and
Device for displaying carbon dioxide

Applicant:

Alfred F. Parmelee,
Kansas City, Mo. (V. St. A.)

Representative: Dipl.-Ing. G. Weinhausen, patent attorney,
Munich 22, Widenmayerstr. 46

William Charles Darby, Santa Maria, Calif. (V. St. Α.), Has been named as the inventor

4. from 0.05 to 0.07% CO

5. from 0.07 to 0.09% CO

In Fig. 1, the production of the regenerating display mass is shown schematically; in

Figure 2 is a schematic of the action of various concentrations of carbon dioxide on a display strip reproduced according to the invention with indication of the discoloration and the corresponding physiological effect on people who are in a room with the specified carbon oxide concentrations are located;

3 shows the arrangement of a display mass between the device parts of a photocell;
4 shows three layers with a display composition according to the present invention, the sensitivity of the three layers being of different magnitudes;

Fig. 5 shows a uniform sensitivity of a layer with a display composition according to the present invention Invention;

6 shows the dependency of the blackening or the becoming opaque of a mass according to the invention again when exposed to gases containing carbon monoxide with different carbon monoxide content.

Although the scientific basis of the blackening and automatic regeneration of the Carbon oxide display mass according to the present invention are not fully clarified, so may the The following explanation serves to explain the invention.

709 910/361

The cuprous chloride, like the palladium chloride, absorbs carbon monoxide, but is colored in the Not contrary to this. When the carbon dioxide acts on a mass, these two components contains, the discoloration depends on the ratio of these two components. Is the Mass relatively less sensitive, so both are in equilibrium with each other. More sensitive However, display masses contain larger amounts of palladium chloride. When the carbon dioxide concentration drops below the percentage that would just blacken the selected mass gives be the palladium chloride, carbon oxide is faster than the cuprous chloride. So it occurs in a short time

are easily soluble. Thus, palladium bromide and palladium iodide can be satisfactory.

The temperature range for drying is 43 to 57 ° C; below this range the Material insensitive, and above this area it turns black. The heating temperature range is about 177 to 238 ° C. Below this range there is a loss of sensitivity, and above it in this area the gel turns black.

Orthotolidine [NH ₂ (CH ₃ ) C ₆ H ₃ ] ₂ can replace the alizarin red in the primary display gel. While orthotolidine itself is not a dye, it is an important starting material from which dyes are formed, and this fact may be common to the like

a lightening, because the palladium chloride free 15 speed in the reaction between the two substances of carbon dioxide will speak of cuprous chloride. While orthotolidine is pretty much in water still contains carbon monoxide.

To produce the display mass according to the

is soluble, it is easily soluble in acid. Accordingly, 65 mg of orthotolidine powder can be added to 1300 mg of 10% hydrochloric acid dissolved and 6500 mg

Equal volumes of 5% palladium chloride solution are diluted in 20 distilled water. It can and 1% Alizarinsulfonatlösung, z. B. Sodium 33O ¹ mg of this solution instead of about 553 mg

of the invention is preferably mixed about

alizarin sulfonate, with 0.1 to 10 ¹ volumes of weakly acidified distilled water. The acidity of the water should preferably be 0.1 to 2.0 n-nitric acid. 0.1 to 10 volumes of 5% cuprous chloride solution and 3 volumes of 0.02% guinea green solution are added to this mixture. Guinea green is a dye with the composition C ₃₇ H ₃₅ N ₂ O ₆ S ₂ Na. The solution is then

Alizarin Red S solution can be applied. The useful range for orthotolidine is about 195 to 450 mg.

When preparing a mass with orthotolidine, it is advisable to use 2 volumes of 5% Palladium chloride solution and V2 to 1 volume of orthotolidine solution. Achieve in terms of discoloration the masses with orthotolidine aren't quite that

granular silica gel or some other anorga, - 30 blackening, the same content with alizarin Carrier absorbed. The carrier substance should be reached red S. How the mass is made have a grain fineness of about 0.25 to 0.3 mm, however, is the same as with Alizarin red S. The wet and especially if the mass for a photo-loaded gel is brick red. After heating in the Should be used electric display, clear or electric oven, the mass looks bright red with at least be translucent. After sucking up 35 a stab of purple.

the mass is first dried at about 43 to the next five are self-regenerating

57 ° C and then half an hour with about gels with different sensitivity to carbon-177 up to 238 ° C. oxide described, with sensitivity

The regenerability and the sensitivity of the areas according to the table below:
By choosing the ratio 4 °
Determined nisses of palladium chloride and cuprous chloride, with a high content of palladium chloride
high sensitivity, but slow regenerability and a high cuprous chloride content low sensitivity, but rapid regeneration
manageability.

As already mentioned, these masses are expediently placed on a base for the photoelectric display applied, being on the same base

Gel no.

4th
5

Sensitivity range

from 0.002 to 0.01% Co from 0.01 to 0.03% Co to 0.05% Co to 0.07% Co up to 0.09% Co

of 0.03
of 0.05
of 0.07

therefore, only the processing of No. 1 will be detailed described.

First gel

Gel # 1 is not regenerative; H. the

several masses of different density are retained next to one another.

sensitivity may be appropriate. For the photo- processing is the same in each case, and

electrical evaluation, transparent fabrics are desirable. The display mass can be fixed between the light source and the photocell
but also between these two elements
be performed. To a volume of 5% aqueous palladium

The relative amounts of palladium chloride and chloride solution become 4 volumes of 0.15 n-saltpeter-alizarin red S can be added from 1: 1, as in general acid, and then 1 volume of 1% strength Description given, varied up to 4VoIu- aqueous sodium alizarin sulfonate (Alizarin red S) mina to 1 volume without the qualitative reaction added to 60 solution.

destroy, albeit a noticeable loss of sensation. Then 2.7 volumes of guinea green will be considered

opportunity occurs at the upper end of its range. An increase in the relative amounts of alizarin red S has no effect. The normality of nitric acid can be acidified for the given 10 volumes Water fluctuates from 0.1 ln to 2, on. That Water can be varied as a unit from 1 to 10 volumes compared to the PaHadium chloride solution. Other halides of palladium are also available

0.02% aqueous solution was added and then 1 volume of 5% aqueous cuprous chloride solution was added.

The liquid is then placed in silica gel, preferably with a mesh size of 20 to 24 Meshes / cm, sucked up and the gel dried at approx. 38 to 57 ° C in the presence of visible and infrared light of a certain intensity. For example

effective because, all in water or weak acid 70 is a 250 W clear glass infrared lamp in one ab-

was sufficient from about 30 to 42.5 cm above the gel. After the mass about 1 hour e was left alone, is heated to about 204-218 C for about ^U V2 hour. After aging for several days, the mass is ready for use.

Second gel

The following amounts provided a non-cumulative gel that had various degrees of blackeness for carbon oxide concentrations of 0.01 to 0.03% (1 part in 10,000 to 3 parts in 10,000) and is not influenced by lower concentrations, regardless of the contact time. There are

4 volumes of 0.15 nitric acid, 1 volume of 5% palladium chloride solution, 1 volume of 1% sodium alizarin sulfonate solution, 2.7 volumes of 0.02% guinea green solution and 1.2 volumes of a mixture of a 5% cuprous chloride solution and a 10% Sodium chloride solution. The exact, measurements used in a laboratory approach, ao was:

To 3120 mg of 0.15 n-nitric acid there were 780 mg of alizarin red S as a 1% solution, furthermore 780 mg

5% palladium chloride solution and 2080 mg 0.02% guinea green solution and 975 mg 5% Cuprous chloride solution mixed with 20% sodium chloride solution was added. Cuprous chloride and sodium chloride were dissolved warm and then cooled to room temperature before doing the above Substances were added. 7.5 mg of silica gel at about 20 to 25 mesh / cm was then added.

It should be noted that in the first gel, the cuprous chloride was added as a simple solution while it was mixed with sodium chloride on the second gel. This latter salt supports the solubility of the copper chloride and also seems to increase the regenerative capacity, as well as the lightening the color from red to a yellowish tone.

Third gel

40

The following amounts form a non-cumulative, regenerating gel that mimics at 0.05% CO turns black after a minimum of about 25 minutes, but not blackened at a lower concentration will. To 4 volumes of 0.15N nitric acid are added 1 volume of 5% palladium chloride solution, 1 volume of 1% sodium alizarin sulfonate solution, 2.7 volumes of 0.02% guinea green solution and 2.3 volumes of 5% cuprous chloride solution mixed with 5% sodium chloride solution were added. the exact dimensions for laboratory approaches were:

3120 mg 0.15 nitric acid, 780 mg 5% palladium chloride solution, 780 mg 1% sodium alizarin, sulfonate solution, 2080 * mg 0.02% guinea green solution, 1810 mg 5% cuprous chloride solution mixed with 5% sodium chloride solution, and 8450 mg silica gel at about 20 to 24 mesh / cm.

Fourth gel

The following amounts can be mixed to obtain a gel that is 0.07% carbon dioxide (7 parts of carbon oxide to 10,000 parts of air) turns black, but independently at lower concentrations does not turn black from the contact time. For 4 volumes of 0.15 n-nitric acid, 1 volume can be added 5% palladium chloride solution, 1 volume 1% sodium alizarin sulfonate solution, 2.67 volumes 0.02% guinea green solution and 3.8 volumes of 5% cuprous chloride solution mixed with 5% Sodium chloride solution, are added. It becomes silica gel with about 20 to 24 mesh / cm in one Add approximately 12 volumes so that all liquid is absorbed. The exact laboratory torium quantities of an experimental approach were as follows:

3120 mg 0.15 η-nitric acid, to the 780 mg palladium chloride solution, 2080 mg 0.02% guinea green solution, 2990 mg 5% cuprous chloride solution with 5% sodium chloride solution and 9100 mg silica gel were added.

Fifth gel

The following amounts give a gel that turns black at 0.09% carbon in air, but through lower concentration is not affected. To 4 volumes of 0.15N nitric acid can be added are: 1 volume of 5% palladium chloride solution, 1 volume of 1% sodium alizarin sulfonate solution, 2.7 volumes of 0.02% guinea green solution and 5.2 volumes of 5% cuprous chloride solution, mixed with 5% sodium chloride solution. The exact dimensions of a laboratory approach were:

3120 mg 0.15 nitric acid, 780 mg 5% palladium chloride solution, 780 mg 1% sodium alizarin sulfonate solution, 2080 mg 0.02% guinea green solution, 2080 mg of 5% cuprous chloride solution mixed with 5% sodium chloride solution, and 9100 mg silica gel.

In the most sensitive gel # 1, palladium and copper are both as a 5% solution in ratio 1: 1 available. In No. 2, the ratio is 4 Pd: 5 Cu. In No. 3, 1 Pd is used on 2.3 Cu. In No. 4 is the ratio 1 Pd: 3.8 Cu and in No. 5 1 Pd: 5.2 Cu. It can be seen that in, the most sensitive gels Palladium predominates, and larger amounts of copper are used in the less sensitive gels are.

Guinea green extends both ends of the sensitivity scale for non-cumulative gels, its ratio to palladium can, if desired, kept constant in all gels, although its influence is weakened in the middle of the range.

The non-cumulative properties can best be explained with reference to FIG. 6 and FIG the regeneration can be distinguished. For purposes of illustration, the blackening and are for gel # 2 the opaque are plotted graphically as a function of time.

This gel is adjusted to a CO concentration of 0.01 to 0.03%. At 0.01% CO, Maximum blackening only a small fraction of total blackening or becoming opaque achieved. Regardless of how long it is exposed to this concentration of CO, it will blacken it doesn't go any further. The blackening when responding to the mean concentration range of 0.02% occurs faster, but is still considerably less than the total blackening, and the greatest possible Blackening only occurs at 0.03% CO after approximately the same period of 25 minutes. The maximum concentration makes the gel completely black, and the blackening occurs at a greater rate. Higher concentrations do not make the gel blacker, but the greatest blackening becomes in Reached far less time.

The regeneration of the original color in gels that are less than blackened to the maximum is done in 1 to 5 minutes, when total blackening is achieved through the highest setting Percentage value, the regeneration takes place in

about 5 minutes. However, regeneration can take place for larger carbon dioxide concentrations up to. Take 5 hours for extremely high percentage values and up to ¹ hour for a slightly higher concentration than corresponds to the set measuring range.

If the non-cumulative gel does not return to its original color, it is non-regenerative, as is the case with # 1. In this case, the gel has a blackening depending on

At the adjusted concentration, streaks turn black in about 25 minutes, and the lifespan the card is 1 to 2 days. The strips are matched at a concentration above their Concentration black in 1 to 5 minutes.

This card uses the non-cumulative and regenerative gels, except No. 1 which when they are of the be exposed to a coordinated concentration, turn black and when the concentration is reduced

value and all concentrations above are totally black.

Amendments

the concentration within the measuring range and i ° tration returns to its original light color at C O concentrations of the highest measuring curve. This cycle can take place as often as

it is asked for.

The card 10 contains a number of strips 11, 12, 13, 14 and 15. These can be grains of masses corresponding to numbers 1, 2, 3, 4 and 5 of the above

The palladium chloride is the most important component examples have. To the right of each stripe are the non-cumulative gels or indicators of the carbon monoxide areas blackening the card, Point of view of the permissible, quantitative amounts indicated and corresponding to the left of the stripes changes ago. If too much palladium chloride causes symptoms or consequences. Hydrogen sulfide (and is applied, the sensitivity increases, but the gels 2 ° nitrogen dioxide) do not stain this cumulative turn black when heated. As a result, the stripes turn brown and falsify the display. Therefore Amount of palladium chloride taken as a standard can be a. special indicator strip 17 on the floor opposite to which the other constituents are varied are added with a suitable reference so that the can. an observer can tell if the blackening

The nitric acid can vary from .0.01n to 2.000 by means of hydrogen sulphide or nitrogen dioxide, for example be ated when the amount of acidified is evoked.

Approximately four times the volume of acetylene, sulfur dioxide, sulfur trioxide and water

Palladium chloride solution reached. Without nitric acid, chlorine changes the color of the carbon oxide indicator, the gels are not uniform in color. However, too much does not interfere with the display. The following gases Acid destroys the regeneration equilibrium. The 30 have no effect: hydrogen, gasoline vapors, preferred acidity of 0.15 η gives the best nitrogen monoxide, water vapor, carbon dioxide, working equilibrium with various carbon formaldehyde vapor, oxygen, nitrogen tetroxide, oxide concentrations. Nitrogen peroxide and natural gas. The display ground for

The amount of sodium alizarin sulfonate solution is hydrogen sulfide and nitrogen dioxide may not be critical. If less than 1 volume of a 35 is made by dissolving 5 g of ammonium molybdate 1/3 of its own solution in 1 volume of palladium chloride in 100 ecm of water and using 10 gl% of methyl solution, the reaction with carbon oxide is not uniform. Amounts of this dye
more than 1 volume does not change the end product

noticeably. The practical area of variation 40 is pale orange in color. Carbon oxide affects compared to 1 volume of palladium chloride, about this gel is not, hydrogen sulfide and nitrogen-0.8 up to 2 volumes.

The guinea green dye solution is so weak that it only fluctuates widely in its volume cause little or no changes in the product. 1 volume gives an orange gel, while 5 volumes give a darker gel that is greener in color. All gels within in this area react equally and effectively.

The most critical component for the sensitivity 50 is the strips 11 and 12 in 2 to 10 minutes, the mixture of cuprous chloride and sodium th black, while the strip 13 only after chloride. If less than V ₁₀ volume turns black this 25 minutes. If the concentration mixture is used, the cumulative gel is reduced to 0.01%, the strip becomes 13 and not self-regenerating. V ₁₀ volume gives a non-accumulating, non-regenerating gel which does not accumulate in about 5 minutes its pale yellow color, e.g. Take eg 55, the strip 12 in about 5 hours and only gel No. 1. The strip 11, the non-regenerating strip, lies between 0.1 and 10 volumes, the sensitivity range, as it is again in FIG. 1, remains black . Thus, any number of times within is given. Above 10 volumes, the maximum CO content changes in sensitivity for a few about 10 minutes. not only displayed, but measured very precisely

The heating temperature is practically between 60 and 60. After 5 hours, any decrease in the about 204 and 218 ° C, below this range - CO content below the maximum at all If the gels do not have the desired sensitivity, regenerative strips appear. Such cards and above about 238 ° C they do not have that are also valuable in garages, offices near motor

orange solution admits. The solution is soaked up in silica gel, and the gel can be stored under heating lamps about 43 to 57 ° C can be dried. The finished gel

but dioxyd blacken the gel, acetylene gives it a brownish color, sulfur dioxide and sulfur trioxide make it purple and chlorine green.

In operation, the map of Figure 2 is visually observed. The response time for the given concentration is about 25 minutes. However, more sensitive stripes turn black more quickly; so if 0.05% carbon dioxide is in the room

cumulative effect.

Display card

FIG. 2 shows a map which takes advantage of the five sensitivities of the gels described above. This map continuously shows the actual

cabs of trucks and inside of airplanes. In cases where gas bags must be taken into account, a quick display is desirable.

The non-cumulative display mass can be used successfully together with photocells for the display

amount of carbon dioxide present. The 7 ° display of a wide range of carbon oxides can be used

if you apply two or more different sensitive gels to one strip. The gels can be a mixture of grains of different sensitivities, or one can! Tape with separated Equip strips of different sensitivity. The belts operate a photocell by reflecting light, or if the tape is transparent, the light can pass through the tape.

In Fig. 3 is a piece of clear tape

18 with gel grains glued to a surface

19 shown. These granules can be non-cumulative gels of mixed sensitivity, e.g. B. No. 1, No. 3 and No. 5 of the above. Examples. A light source 21 can light through the tape and the Throw gel grains at a photocell 22 with a window about the width of the strip. When exposed to carbon dioxide, the most sensitive gels are quickly blackened and changed Light transmission, whereby the photocurrent changes, the z. B. measured with a micro-ammeter will. After 25 minutes the gel, which corresponds to the existing carbon oxide content, is blackened and gives the correct long-term reading.

Fig. 4 shows a band 23 with a plurality of strips 24, 26 and 27 of different sensitivity for one photoelectric display.

In operation, the devices of FIG. 3 speak and 4 over 1 to 5 minutes to carbon dioxide levels by blackening the gel and change in photocurrent that is well above the range of the most sensitive gel lie.

Maximum blackening occurs after about 25 minutes of contact. A decrease in the concentration of carbon dioxide will appear in 5 to 10 minutes through the sensitive gel, but it will be during 5 or 6 hours not recognized by the less sensitive blackened gels as this is the regeneration time for overly blackened gels. For this reason it is desirable to strip the Figures 3 and 4 slowly move past the light and photoelectric device leave so that a fresh amount of strips can be exposed to the surrounding carbon dioxide,

45 Silica Gel Description

The silica gel used appears to be essential as the carrier of the chemical mixture. Other Carriers give poorer results.

Coarse silica gel grains broken into smaller grains do not give satisfactory results brought forth. Silica gel has specific properties that are important. The manufactured display gels were steamed for 5 to 15 minutes and gained about 1 to 2 percent by weight. Thus, the excellent moisture absorbing effect of free silica gel has been eliminated. The reaction with carbon monoxide was found microscopically to be a surface reaction. A full blackened grain showed only surface blackening. Another dealing with the split Grain with carbon oxide shows a reaction only on the original surface. Apparently the reactive chemicals do not penetrate the gel grains, although the dye and the water penetrate this. It may be that carbon dioxide is absorbed throughout the grain will, but this does not seem likely in terms of weight change on recovery.

The changes in weight of the indicator gel when exposed to carbon dioxide are extremely characteristic. A non-cumulative gel that weighed 1950 mg before treatment had a weight of 2470 mg (= a 27% increase) after complete blackening. When regenerated, it weighed 2210 ¹ mg, indicating that carbon oxide was indeed released. This also indicates that the palladium compound is the active carbon oxide absorbent, since silica gel does not split off an absorbed gas until it is heated. The size of the silica gel grains is not too important. Grains of 8 mesh / cm have been used with success, but 20 to 24 mesh / cm is preferred. Very fine grains or very fine powder, which are created by rubbing or splitting larger parts, are not satisfactory.

Gel drying in the range of 43 to 57 ° C appears to be necessary as opposed to one single heating stage. The heating must also take place separately from the drying.

In the dry stage when processing cumulative gel is the presence of short-wave Infrared rays are not strictly necessary, but in practice a better gel can be made with one Heating lamp can be obtained. It should be recognized that the heat of any kind in the area from 43 to 57 ° C is a long wave infrared.

Filament heat lamps produce most of the energy at around 12,000 Angstroms, very little energy above 25,000 angstroms. A large part of the energy of these lamps is also in the visible area, the eliminated when red glass is used, but allowed through when clear glass is in the Lamps is used. The data provided by the manufacturer gives 0.08 W / square inch of infrared energy on a surface if a 250 W GE Industrial Infrared Lamp 35 cm above the surface. For this reason, the approximate value of 0.06 has been used as approximate that for making non-cumulative gels at 43 cm apart, and you can Use a distance of 30 to 43 cm from the surface for this lamp.

The use of infrared lamps for the drying stage of the non-cumulative gels seems desirable, and the application of visible light appears desirable in addition.

Claims (1)

Claim! :: 1. A process for the production of a carbon oxide display mass, which consists of a palladium chloride and Alizarinsulfonate, in particular Alizarinrot S, or orthotolidine-containing solution through Absorption on an organic carrier, in particular silica gel, followed by drying and heating is obtained, characterized in that the solution additionally cuprous chloride, optionally together with another chloride, e.g. B. sodium chloride, and second Dye guinea green is added. 2. The method according to claim 1, characterized in that approximately equal volumes 5 ° / »iger Palladium chloride solution and 1% sodium alizarin sulfonate solution in 0.1 to 10 volumes acidified, preferably to 0.1 to 2.0 · n-nitric acid adjusted water, additionally with 0.1 to 10 volumes of about 5% cuprous chloride solution and 3 volumes of 0.02% guinea, - 709 910/361 Green solution added and then with so much granular, preferably translucent silica gel, preferably from. a grain size of about 0.25 to 0.3 mm (50 to 60 mesh) mixed that all the liquid is absorbed, the mass is then dried at about 43 to 57 ° C and then heated to about 177 to 238 ° C. for about 1/2 hour. 3. The method according to claim 2, characterized in that that the sensitivity and regenerability of the carbon oxide indicator mass by choosing a certain ratio of palladium chloride solution to cuprous chloride solution, namely by a, high palladium chloride content to high sensitivity and low Regenerability or a high cuprous chloride content to lower sensitivity and faster regenerability is set. 4. The method according to claim 2 or 3, characterized in that several with different Proportional amounts of palladium chloride solution and cuprous chloride solution produced carbon oxide mixed together for display purposes, on a pad or separately on different ones Documents are applied and these are arranged side by side and form a carbon oxide display card can be compiled with several display areas. 5. Application of the carbon indicator composition according to claim 1 for preferably continuous Measuring the carbon oxide content of a gas, characterized in that the carbon oxide indicator mass using a translucent silica gel, optionally with a mixture of several display masses of different Sensitivity, applied to a transparent base and the base with the Carbon oxide display mass arranged between a light source and a photoelectric cell or is preferably moved between them. Considered publications:
British Patent No. 673,419. 1 sheet of drawings 1 709 910/361 3.58