US2400288A - Process of making dinitroethyleneurea - Google Patents

Description

Patented May 14, 1946 mocnss OF MAKING nm'mon'rmnua- 1mm George v. Caesar. Staten Island, and Max Goldfrank, New York, N. Y., assignors to Stein, Hall & Company, Inc., New York, N. Y., a corporatlon of New York No Drawing. Application February 25, 1944, Serial No. 528,936

18 Claims: (Cl. 260-309) The present invention relates to a new process for the direct liquid phase nitration of ethyleneurea to form dlnltroethyleneurea.

It is known in the prior art that ethylenedinitramine is a valuable explosive and it has a high degree of resistance to detonation by impact or shock and yet has a high brisance or explosive strength. It may be produced by refluxing dinitroethyleneurea with water.

The invention is concerned with the method of making the intermediate product, dinitroethyleneurea, which in itself is valuable as an explosive, or it may be converted into the more valuable ethylenedinitramine by hydrolyzing in boiling water,

In accordance with the prior art, it has been proposed to produce dinitroethyleneurea by the nitration of ethyleneurea with very strong nitric acid. This produces relatively low yields and reugires the use of the expensive strong nitric 8.01

It has also been proposed in accordance with the prior art to nitrate ethyleneurea with mixed nitric and sulfuric acids. This process requires a careful control of the composition of the mixed acids, more particularly about 68.5% sulfuric acid, 22% nitric acid and 9.5% water. Although the yields are improved as compared with the nitration with strong nitric acid, the reaction time is slow and the nitration must be continued for about two hours.

In accordance with either or these prior art processes the reaction is believed to be as follows:

It will be seen that water is the primary by-product. This production or water in the prior art processes involves a progressive dilution of the nitrating solution. The presence of water is undesirable not only because it dilutes the acid and reduces the rate of the nitrating action, but, since these processes are reversible, the presence or water also shifts the equilibrium and results in poorer yields. The diillculties resulting from the formation of water in the nitration with strong nitric acid is particularly striking, because as soon as the water is formed the acid ceases to be strong.

The attempt to circumvent the presence of water by mixing with the nitric acid a water absorptive agent, or a dehydrating acid such as sulfuric acid, is indicated in the prior art referred to above. The formation of water, however, alters the proportions of the components of the nitrating solution and the prior art has indicated the proportions as critical. A nitric acid nitrating solution, whether or not a dehydrating acid such as sulfuric acid is used, cannot be refortified indefinitely, either by the addition of concentrated nitric acid or a water absorptive agent, because of the resulting undersirahle in-- crease in volume. Ultimately the diluted acids must be withdrawn and replaced. When practiced in a large scale operation the effective disposal of the large quantities of diluted and spent acids presents a very difficult problem.

Another disadvantage resulting from the use of mixed acids in the nitration of ethylene urea, aside from the formation of water, is the possible production of undesirable reaction products with sulfuric acid. These may adversely afiect the stability of the dinitroethyleneurea or require processing to remove them.

In accordance with this invention ethyleneurea is nitrated with nitrogen pentoxide (N205) in solution in an inert non-aqueous solvent, such as hydrocarbon or a chlorinated hydrocarbon.

The ultimate products of the reaction of ethyleneurea and nitrogen pentoxide are dinitroethyleneurea and nitric acid and it is thought that the reaction may proceed as follows:

The process is particularly advantageous since a solvent may be selected in which the ethyleneurea and the nitrogen pentoxlde are soluble, but in which the dlnitroethyleneurea is relatively insoluble. The ethyleneurea may be dissolved in the solvent and mixed with a solution of nitrogen pentoxide in the solvent and the reaction will be practically a, quantitative precipitation. It has been found that if a solution of ethyleneurea in chloroform, for example, is added to a solution of nitrogen pentoxide in the same solvent, the dinitroethyleneurea precipitates instantaneously in crystalline form and in substantially quantitative yields. The various practical advantages of such a process are so obvious that to one skilled in the art they need not be elaborated.

The precipitated crystalline dinltroeihylencurea, upon removal from the nitrating solution. may be hydrolyzed in accordance with the known practice by boiling in water from which the ethylenedinitramine forms in beautiful crystals upon cooling.

As illustrative of the manner in which the invention may be practiced reference may be had to the following illustrative examples. For convenience, the amounts of the reactants have been given as those which may be easily utilized in the laboratory. The following examples are merely illustrative and are not intended as a limitation on the scope of the invention.

Example I Ethyleneurea in an amount of 4.75 grams was dissolved in 85 cc. of chloroform and the solution was added with agitation to 250 cc. of a solution of chloroform in which 47.2 grams of nitrogen pentoxide was dissolved. The initial temperature of the chloroform-nitrogen pentoxide solution was 8 C. The crystalline dinitroethyleneurea was precipitated instantly upon the mixing of the two solutions and the temperature rose to 29 C. The dinitroethyleneurea was then removed by filtration and washed with cold water. The nitration period did not exceed two minutes. The yield was 8.75 grams or 89.8 of theory. Mechanical losses, plus the slight solubility of the dinitroethyleneurea in the cold water, probably account for the difference.

Example II Ethyleneureau in an amount of 4.88 grams in solution in 85 cc. of chloroform was added to a chloroform-nitrogen pentoxide solution of the same amount and strength as in Example I. The initial temperature was -3 C. Crystalline dinitroethyleneurea formed immediately upon mixing the solution but the nitrating period was extended for 15 minutes during which the temperature was allowed to rise to 17 C. The yield was 8.93 grams or 89.3% of theory, showing that the nitration period may be very brief and still obtain a good yield.

Example In A solution containing 4.99 grams oi ethyleneurea and 85 cc. of chloroform was added to a chloroform-nitrogen pentoxide solution in the same amount and strength as in Examples I and II. The initial temperature was -4 C. Crystalline dinitroethyleneurea formed immediately and the nitration period was extended to 30 minutes during which the temperature was allowed to rise but not exceed 1'?" C. The yield was 9.5 grams or 93.3% of theory.

Example IV A solution of nitrogen pentoxide in chloroform was prepared by dissolving 37.2 grams of nitrogen pentoxide in sufficient chloroform to make 335 cc. Into this was stirred 5 grams of solid ethyleneurea. At first lumps formed which were gradually dispersed during the agitation. The initial temperature was 2 C. and was permitted to rise gradually but not exceed 15 C. The nitration was permitted to continue for 47 minutes and the yield of dinitrocthyleneurea obtained was 9.5 grams or 92.8

In all of the above examples the nilraiing solution can be further used in nitrating an additional quantity of ethyleneurea by adding nitrogen pentoxide to the solution. The nitric acid may be removed and/or regenerated into nitrogen pentoxide as described hereinafter. The process, therefore, is adaptable for a continuous method of nitration.

Any portion of the ethyleneurea in solution, but not entering into a reaction is thought to remain in the solution and upon reuse of the nitrating solution will eventually be utilized. Therefore. upon the selection of optimum temperatures, etc. not only will high yields per pass be obtained, but a substantially yield would be possible in a continuous process.

The nitrogen pentoxide and the ethyleneurea need not necessarily be a chemically pure com pound to be utilized in the process. However, if great purity in the final product is important, particularly for the manufacture of explosives. it is preferred to utilize ingredients which are as chemically pure as possible so as to avoid unde sirable components entering into the reaction.

The process may be practiced in any manner in which the ethyleneurea is contacted with the nitrogen pentoxide in the solvent. This may be carried out in a. batch operation, following which the nitrated product is separated. However. the process is so well adapted to a continuous op eration, and since continuous processes are desirable for commercial operations, this may be a preferable form.

In one such continuous process the 'ethyleneurea. may be continuously added to the nitrating solution in a reaction zone following which the mixture is transferred to a filterin zone and the nitrated product separated. The nitrating solution may be continuously or intermittently refortifled with nitrogen pentoxide and again returned to the reaction zone to be reused.

In another process both the nitrogen pentoxide and the ethyleneurea may be continuously introduced in the correct proportions into a solvent in a mixer. The nitrated product may be separated at the bottom as a precipitate.

In view of the above explanation, it is obvious that many ways of carrying out the nitration may be suggested to one skilled in the art. and all such variations are intended to be included in the scope of the present invention.

The neutral solvent which is utilized in accordance with the invention may be selected from many available non-aqueous solvents such as those of coal tar 0r petroleum origin. .It is preferred to utilize a material which is not reactive with any of the other materials present, i, e.. the nitrogen pentoxide, the ethyleneurea, the dinitroethyieneurea and the nitric acid. It is preferred to utilize a. olvent in which not only the nitrogen pentoxide is soluble but in which the ethyleneurea is soluble and the dinitroethyleneurea is insoluble. However. both the ethyleneurea and the dinitroethyleneurea may be soluble or insoluble and appropriate modifications made in the process. As specific examples. it has been found that chloroform may be used advantageously. Gen erally it is advantageous to utilize a solvent having a boiling point or range which sufficiently high so that it can be maintained readily in the liquid phase during the nitration but sufficiently low so that any solvent adhering to the nitrated product may be readily removed during the drying at a temperature above the boilin point of the solvent but below the temperature at which the dinitroethyleneurea would be harmed. Chloroform (CHCIJ) for example, is particularly advantageous in this connection because of its boiling point of about 61.2 C. The foregoin solvent is mentioned merely by way of illustration and it is intended that the invention shall not be limited thereto. In view of the present disclosure as to the requirements of the solvent, those skilled in the art may readily select a solvent suitable for the conditions under which a particular adaptation of the process is to be carried out.

The proportions of the reacting ingredients utilized may be varied over a wide range, depending upon the conditions of operation and the results which it is desired to obtain. The theoretical amounts of the reacting ingredients. of course, may be calculated from the formulas illustrating the reaction.

In general the amount of the nitrogen pentoxide may be varied by varying its concentration in the nitrating solution and also by varying the amount of nitrating solution used with the ethyleneurea. It has been found convenient to dissolve the nitrogen pentoxide in the proportion of about to 50 grams per 100 cc. of solution, preferably the range is about to 25 grams. The process proceeds quite well with any substantial concentration furnishing suilicient nitrogen pentoxide for the reaction. As the nitration proceeds, additional nitrogen pentoxide may be added, if desired, to fortify and maintain the initial strength of the solution. Alternatively, a stronger solution may be used so that the concentration does not fall below the minimum figure which is preferred to be maintained during the entire course of the reaction.

The amount of the nitrating solution utilized in relation to the material to be nitrated may vary over a wide range, the minimum being sufl'lcient to provide the desired amount of nitrogen pentoxide to accomplish the nitration. This will depend upon whether nitrogen pentoxide is to be added during the course of the reaction or whether the process contemplates the presence of a suiiicient initial concentration to complete the reaction. In general there is no objection to a great excess of the nitrating solution to cause the reaction to proceed at the desired degree. When the process is carried out continuously on a large scale a great amount of solution may be used to fill a system or the apparatus. Any larger amount may be used and it will be apparent, in view of the disclosure, that the amount is not critical and may be varied throughout a wide range without affecting the economy of the process.

As a precautionary measure the temperature at which the process is carried out should not be too high. In general a temeprature range of the order of 20 to 30 C. may be used, preferably 0 to 20 C, The temperature may be selected with reference to the exact type of process, the factor of safety, etc.

In general it is not necessary to carry out the process under pressure. Because of the ease of operation in the absence of pressure, this is preferred. It is an advantage of the present process. however, that it may be carried out in a closed system to prevent loss of the solvent.

It will be noted in accordance with Equation 2 that the primary by-product of the reaction in accordance with the invention is nitric acid which remains dissolved in the solvent along with any excess nitrogen pentoxide and any unreacted ethyleneurea. It is, therefore, possible that upon the accumulation of nitric acid in the nitrating solution the reaction (1) may also take place with the formation of water as a secondary by-product. This may result in the disadvantages referred to heretofore in connection with the Presence of the water.

However, since the reaction is one in which both reactants may be in solution and the principal product is insoluble in the nitrating solution and the by-product soluble, it is not so essential to mass action principles to employ means to remove the nitric acid as soon as possible after it is formed.

In accordance with an embodiment of the invention which would be preferably utilized in a continuous process, the nitric acid may be removed substantially as fast as it is formed so as to prevent the reaction (1) and its attendant difficulties due to the formation of water.

In accordance with one embodiment of the process for removing nitric acid the nitrating solution is contacted with phosphorus pentoxide (P205). By this means the primary by-product of the reaction, nitric acid, is absorbed by the phosphorus pentoxide and, at least in part, reconverted to nitrogen pentoxide in accordance with, it is thought, the following reaction:

If the solvent selected is one in which the nitrogen pentoxide and nitric acid are soluble, such as chloroform, but in which the phosphorus pentoxide and the metaphosphoric acid are insoluble, the nitrating solution may be circulated over a bed of phosphorus pentoxide to have the nitric acid removed.

By means of such a process, it is possible to provide a simple means of indefinitely maintaining the purity of the nitrating solution and the only variable will be the concentration of the nitrogen pentoxide in the solvent. Even this may be eliminated as a variable by fortifying it with a solution of N204.

When the nitric acid is to be removed with phosphorus pentoxide the process may be carried out conveniently in either a batch or a. continuous operation. In a batch operation the nitrating solution may be contacted with the phosphorus pentoxide between batches. However, this embodiment of the process is so well adapted to a continuous operation and these are so desirable on a commercial scale that this seems to be the preferable commercial form. In one such embodiment the nitrating solution may be continuously circulated, first through a mixing zone with the ethyleneurea which is added either in solution or as a solid and in which zone the dintroethyleneurea is separated by illtraticn or settling, following which the solution is then circulated through a regenerating zone which may be in the form of a bed of phosphorus pentoxide. In such a process the nitric acid, as fast as it is formed as the primary product, is carried out of the nitrating zone and away from the ethylencurea. The nitric acid is removed by treatment with the phosphorus pentoxide beforethe solution is recontacted with additional ethyleneurea. If ethyleneurea is to be treated in a solid form it may be passed coninuously through a treating chamber through which the nitrating solution is continuously flowing, preferably counter-current. A series of regenerating chambers may be provided so that one may be used while another is being charged with a fresh quantity of phosphorus pentoxide.

In another embodiment of the process the nitric acid formed may be removed from the nitrating solution by means of a fluoride salt. Sodium fluoride is the cheapest of the materials for this purpose and this adaptation oi the invention will be described further using sodium fluoride as illustrative.

By means of this process, in which nitrogen pentoxide is in solution in the non-aqueous inert solvent and the sodium fluoride is insoluble in the solvent, it is possible to provide a simple means of indefinitely maintaining the purity of the nitrating solution and the only variable will be the concentration of the nitrogen pentoxide in the solvent. Even this may be eliminated as a variable by fortifying it with a solution Of N205.

The process using the sodium fluoride may be operated in a batch or continuous manner in any of the ways suggested heretofore in connection with the use of phosphorus pentoxide. For example, the ethyleneurea may be placed in the nitrogen pentoxide solution and the dinitroethyleneurca removed, following which sodium fluoride may be added to the solution to remove the nitric acid and the solution reused. In a continuous process the solution may be circulated through a vessel containing sodium fluoride in the manner previously described in connection with the removal of the nitric acid with phosphorus pentoxide.

The amount of sodium fluoride which may be utilized also is not critical. In general, it is desired to utilize sufficient sodium fluoride to insure substantially complete adsorption of the nitric acid. The amount required many depend also on the frequency with which it is replaced, and the exact process adapted. A counter-current system should use a. lesser amount. In general, it may be preferred to utilize a proportion of about 1 part of sodium fluoride to about 2 parts oi the by-product nitric acid theoretically obtainable. This proportion is merely illustra tire and may be varied over a wide range.

Without wishing to be bound by any theory as to the results obtained when using sodium fluoride to remove nitric acid, the following explanation may be of assistance in understanding this aspect of the invention.

It is thought that the sodium fluoride holds the acid through the so-called "hydrogen bond or "coordinate" linkage, sometimes referred to as a secondary valence. The fluorine atom being strongly clectronegative acts as a proton acceptor and the hydrogen in the acid is attracted to the fluorine and held through ionic forces. This explains why nitric acid, for example, which contains hydrogen may combine with the fluorides through a so-called secondary valence, whereas nitrogen pentoxide, which does not contain hydrogen, does not. The hydrogen bonded complex of the fluoride and the acid presumably, therefore, may be viewed as where the full dash indicates a primary valence and where the dotted dash indicates the socaled hydrogen bond or secondary valence.

The phenomena described is referred to as an adsorption, and this is not intended to mean a strictly physical relationship between the acid and the fluoride. The word is used as generic to a. physical or chemical union, or a combination thereof, particularly the possible chemical complex involving the phenomena of the socalled hydrogen bonds.

In describing the applicability of the invention, using a fluoride to remove the nitric acid, we have illustrated it with the use of sodium fluoride merely for convenience because of its availability, low cost, practicality, and eiflclency. It is to be understood, however, that certain other fluorides may be used, such as zinc fluoride, magnesium fluoride, potassium fluoride, ammonium fluoride, etc. The words fluoride salt" are intended to be generic to fluorides of these metals.

In view of the foregoing disclosure and many variations in carrying out the invention, it may be suggested to one skilled in the art that all such variations are intended to be included within the scope of the invention as fall within the following claims.

We claim:

1. A process of nitrating ethyleneurea which comprises treating it with a solution of nitrogen pentoxide dissolved in a non-aqueous solvent.

2. A process of nitratlng ethyleneurea which comprises treating it with nitrogen pentoxide dissolved in chloroform.

3. A process of nitrating ethyieneurea which comprises mixing a. solution of ethyleneurea in a non-aqueous solvent with a solution of nitrogen pentoxide in a non-aqueous solvent.

4. A process of nitrating ethyleneurea which comprises treating it with it with a solution of nitrogen pentoxide dissolved in a non-aqueous solvent in the proportion of about 5 to 50 grams of nitrogen pentoxide to cc. of solution, and maintaining a temperature of about 20 to 30 C. during the nitration.

5. A process of nitrating ethyleneurea which comprises treating it with a solution of nitrogen pentoxide dissolved in a non-aqueous solvent in the proportion of about 5 to 50 'grams of nitrogen pentoxide to 100 cc. of solution, maintaining a temperature of about 20 to 30 C. during the nitration, and separating the dinitroethyleneurea from the solution.

6. A process of nitrating ethyleneurea which comprises treating it with nitrogen pentoxide dissolved in chloroform in the proportion of about 5 to 50 grams of nitrogen pentoxide to 100 cc. of solution.

'7. A process of nitrating ethyleneurea which comprises treating it with nitrogen pentoxide dissolved in chloroform in the proportion .01 about 5 to 50 grams of nitrogen pentoxide to 100 cc. of solution, maintaining a temperature of about -20 to 30 C. during the nitration, and separating the dinitroethyleneurea from the solution.

8. A process of nitrating ethyleneurea which comprises dissolving it in chloroform and addin the solution so formed with agitation to a solution of nitrogen pentoxide in chloroform, the amount of the nitrogen pentoxide being at least that theoretically required to convert the ethyleneurea to dinitroethyleneurea, removing the crystalline dinitroethyleneurea which forms as a precipitate, and washing and drying the precipitate.

9. A continuous process for manufacturing dinitroethyleneurea, which comprises continuously contacting ethyleneurea. and nitrogen pentoxide in a solvent in which both the soluble but in which the dinitroethyleneurea is insoluble, and separating the precipitated dinitroethyleneurea.

10. A continuous process for manufacturing dinitroethyieneurea, which comprises continuousiy contacting ethyieneurea and nitrogen pentoxide dissolved in chloroform, and separating the precipitated dinitroethyleneurea.

11. A continuous process for manufacturing dinitroethyieneurea which comprises continuously adding ethyleneurea to a solution of nitrogen pentoxid in a non-aqueous solvent in which the ethyleneurea is soluble but in which the dinitroethyleneurea is insoluble, and separating the precipitated dinitroethyieneurea.

12. A continuous process for manufacturing dinitroethyleneurea which comprises continuously adding a solution of ethyleneurea in a nonaqueous solvent to a solution of nitrogen pentoxide in a non-aqueous solvent. said solvent being one in which the ethyleneurea is soluble but in which the dinitroethyleneurea is insoluble, and separating the precipitated dinitroethyleneurea.

13. A continuous process for manufacturing dinitroethyleneurea which comprises continuousLv contacting ethyleneurea and nitrogen pentoxide in a non-aqueous solvent in which the Certificate of Correction Patent No. 2,400,288.

ethyleneurea is soluble but in which the dinitroethyleneurea is insoluble, and separating the precipitated dinitroethyieneurea, removing nitric acid formed in the reaction and reusing the solvent in the nitration of an additional quantity of ethyleneurea.

'14. A continuous process for manufacturing dinitroethyieneurea which comprises continuously adding ethyleneurea to a solution of nitrogen pentoxide in chloroform, and separating the precipitated dinitroethyleneurea.

15. A continuous process for manufacturin dinitroethyleneurea which comprises continu ously mixing a solution of ethyieneurea in chloroform with a solution of nitrogen pentoxlde in chloroform, and separating the precipitated dinitroethyleneurea.

16. A continuous process for manufacturing dinitroethyieneurea which comprises continuously contacting ethyleneurea and nitrogen pentoxide in chloroform, separating the precipitated dinitroethyleneur'ea. removing nitric acid from the chloroform and reusing the chloroform for nitrating an additional amount of ethyleneurea.

GEORGE V. CAESAR. MAX GOLDFRANK.

May 14, 1946.

GEORGE V. CAESAR ET AL.

It is hereby certified that errors appear 1n the numbered patent requiring correction as follows: after as and before hydrocarbon insert a; page Ethylcneureau read Ethyleneurea; page read temperature; line (3 with second occurrence, 5

Patent should be read with these corrections therein that the 3, first column, lllllt'. l r 34 b f f 2 read ,Q); page 4, seconr co umn, me e ore 9 t rike out the words with it; and that the said Letters the record of the case in the Patent Office.

Signed and sealed this 2d day of July, A. D. 1946.

[small] printed specification of the above Page 1, second column, lme 27, 2, first column, lme 35, for 57, for temoprature same may conform to LESLIE FRAZER,

first Assistant Commissioner of Patents.

but in which the dinitroethyleneurea is insoluble, and separating the precipitated dinitroethyleneurea.

10. A continuous process for manufacturing dinitroethyieneurea, which comprises continuousiy contacting ethyieneurea and nitrogen pentoxide dissolved in chloroform, and separating the precipitated dinitroethyleneurea.

11. A continuous process for manufacturing dinitroethyieneurea which comprises continuously adding ethyleneurea to a solution of nitrogen pentoxid in a non-aqueous solvent in which the ethyleneurea is soluble but in which the dinitroethyleneurea is insoluble, and separating the precipitated dinitroethyieneurea.

12. A continuous process for manufacturing dinitroethyleneurea which comprises continuously adding a solution of ethyleneurea in a nonaqueous solvent to a solution of nitrogen pentoxide in a non-aqueous solvent. said solvent being one in which the ethyleneurea is soluble but in which the dinitroethyleneurea is insoluble, and separating the precipitated dinitroethyleneurea.

13. A continuous process for manufacturing dinitroethyleneurea which comprises continuousLv contacting ethyleneurea and nitrogen pentoxide in a non-aqueous solvent in which the Certificate of Correction Patent No. 2,400,288.

ethyleneurea is soluble but in which the dinitroethyleneurea is insoluble, and separating the precipitated dinitroethyieneurea, removing nitric acid formed in the reaction and reusing the solvent in the nitration of an additional quantity of ethyleneurea.

'14. A continuous process for manufacturing dinitroethyieneurea which comprises continuously adding ethyleneurea to a solution of nitrogen pentoxide in chloroform, and separating the precipitated dinitroethyleneurea.

15. A continuous process for manufacturin dinitroethyleneurea which comprises continu ously mixing a solution of ethyieneurea in chloroform with a solution of nitrogen pentoxlde in chloroform, and separating the precipitated dinitroethyleneurea.

16. A continuous process for manufacturing dinitroethyieneurea which comprises continuously contacting ethyleneurea and nitrogen pentoxide in chloroform, separating the precipitated dinitroethyleneur'ea. removing nitric acid from the chloroform and reusing the chloroform for nitrating an additional amount of ethyleneurea.

GEORGE V. CAESAR. MAX GOLDFRANK.

May 14, 1946.

GEORGE V. CAESAR ET AL.

It is hereby certified that errors appear 1n the numbered patent requiring correction as follows: after as and before hydrocarbon insert a; page Ethylcneureau read Ethyleneurea; page read temperature; line (3 with second occurrence, 5

Patent should be read with these corrections therein that the 3, first column, lllllt'. l r 34 b f f 2 read ,Q); page 4, seconr co umn, me e ore 9 t rike out the words with it; and that the said Letters the record of the case in the Patent Office.

Signed and sealed this 2d day of July, A. D. 1946.

[small] printed specification of the above Page 1, second column, lme 27, 2, first column, lme 35, for 57, for temoprature same may conform to LESLIE FRAZER,

first Assistant Commissioner of Patents.