632 



THE INDIA RUBBER WORLD 



[August 1, 1919. 



eight 



the 



distilled off and the residue dried i.. com 

 water oven. 



The rubber residue left after boiling with alcoholic potash is 

 washed free from potash by water, dried to constant weight in 

 the water oven, and cooled in vacuo. The ash and sulphur in 

 the dried residue arc then estimated and thence the weight oi 

 organic matter in the residue is calculated. This weight is 

 deducted from the weight of organic matter in the residue after 

 extraction with acetone (obtained by deduction of ash and com- 

 bined sulphur) and from the difference the loss of organic mat- 

 ter by extraction with alcoholic potash per 100 parts of rubber is 

 calculated. 



The india-rubber proofing should be free from grit and large 

 size particles. In the case of capes a three-inch square of ma- 

 terial should have at least 0.13 grams of proofing between the 

 two fabrics 



THIOGEN PROCESS OF MAKING SULPHUR. 



The ihiogen process of making sulphur consists essentially in 

 the treatment of sulphur dioxide gas, from any source, with a 

 hydrocarbon gas in the presence of a basic sulphide catalytic 

 material. Any form of hydrocarbon gas or reducing gas may 

 be used, the result in any case being sulphur vapor, carbon di- 

 oxide and water vapor. The so-called wet thiogen process 

 was tried out under the direct supervision of the United States 

 Bureau of Mines in 1915, and the results published in Bulletin 

 113 of that Bureau, 



In brief, it was determined that sulphur could undoubtedly 

 be produced by this process at an estimated cost of about $12 

 per tor. By adaptation of modern commercial practice in the 

 concentration of the sulphur-dioxide gas from weaker gases, be- 

 fore reducing this gas to elemental sulphur, by the action of the 

 reducing gases not only is the size of the installation for a given 

 capacity very much reduced but the oxygen content of the gas 

 is entirely removed, thereby effecting a great reduction in the 

 amount of "-educing material necessary. 



Under the most favorable conditions the cost of producing 

 sulphur by the improved process is now estimated at $5 per ton. 



DETERMINATION OF SULPHUR IN VULCANIZED RUBBER. 



The following method for determining sulphur in vulcanized 

 rubber, by H. P. Stevens, is abstracted from "The .Analyst," vol- 

 ume 43 (1918), page 377. 



About O.S grams of the sample is digested with 20 cc. of nitric 

 acid (specific gravity 1.42) and 0.5 grams of potassium chlorate. 

 The liquid is then boiled for two or three hours beneath a reflux 

 condenser, subsequently evaporated to dryness in a dish after the 

 addition of three grams of pure magnesium nitrate. The residue 

 is cautiously heated over a flame, the presence of the magnesium 

 salt moderating the combustion, and any unburnt carbon is de- 

 stroyed by digestion with nitric acid and potassium chlorate, and 

 the excess of acid evaporated. 



After the addition of 10 cc. of strong hydrochloric acid, the 

 dish is covered with a watch glass and gently heated until red 

 fumes cease to appear. The liquid is then diluted, filtered, made 

 up to 300 cc, and heated to boiling on a hot plate. The sulphuric 

 acid is precipitated by the addition of 5 cc. of ten per cent barium 

 chloride solution, and the precipitate allowed to stand over night 

 before filtration. 



BRITISH USE OF NITER CAKE IN RUBBER RECLAMATION. 



The following information on the use of niter cake in reclaim- 

 ing unvulcanized rubber is derived from a report by Consul Ross 

 E. Holaday, Manchester. England, in "Commerce Reports" 

 (March 15, 1919). 



In reclaiming unvulcanized waste rubber by the acid process 

 a solution is made up by dissolving niter cake in hot water, which 

 gives about a ten per cent content of sulphuric acid. As it is 



necessary to ba\o a 15 to 20 per cent solution of sulphuric acid, 

 Manchester reclaimers bring this up to strength by using commer- 

 cial sulphuric acid. In this way they are enabled to use about SO 

 per cent niter cake in the treatment of waste rubber by the acid 



During the war sulphuric acid was available for use in Eng- 

 land only on a permit issued by the Ministry of Munitions and 

 it was not possible to use a straight sulphuric acid solution with- 

 out the use of niter cake. By careful handling and thorough 

 washing it has been found that niter cake can be used with a 

 considerable degree of safety. 



WATERPROOFING DRAWINGS. 



h'ln the purpose of rendering drawings waterproof to be used 

 ill damp localities, mines, etc., J. S. Carpenter recommends in 

 "Engineering News," September 20, 1918, a solution of pure 

 unvulcanized caoutchouc in benzene. The solution is diluted 

 sufficiently with benzene to yield a thin liquid that will spread 

 well under a brush. With (his liquid the drawing is coated on 

 both sides. A thicker solution or cement of crude rubber is used 

 to stick together parts of large drawings. The same solution may 

 also be used for cleaning soiled drawings, the deposited film of 

 rubber being rolled up and used as an eraser. 



SYNTHETIC CAOUTCHOUC. 



The "Journal of the Society of Chemical Industry," March 31, 

 1919, gives the following abstract of an article by C. Duisberg, 

 in the "Elektrochemische Zeitschrift" ("Electrochemical Jour- 

 nal"), 1918. volume 24, pages 369-372. 



Synthetic rubber from dimethylbutadiene (methylisoprene) as 

 first made on a commercial scale was very susceptible to oxida- 

 tion and combined very slowly with sulphur. These difficulties 

 were overcome by the addition of organic bases (especially piperi- 

 dine and similar substances, and in this way hard rubber equal 

 in strength to that made from natural rubber and with an elec- 

 trical resistance about 20 per cent higher, has been made. 



The production of soft vulcanized rubber from the synthetic 

 product has not been equally successful. Leather-like products 

 are usually obtained and although the elasticity can be improved 

 by addition of dimethylaniline and other substances, the material 

 does not work well on the rolls, does not vulcanize satisfac- 

 torily, and is inferior in "nerve" to vulcanized rubber made from 

 the natural product. 



CHEMICAL PATENTS. 

 THE UNITED STATES. 



LE.^THER .SuBSTiTUTE.s. .\ permanently fibrous substitute for 

 leather, comprising a short length fiber, selected sheet Ceylon 

 rubber, gum Concho, shoddy, Pontianak. magnesia, red oxide of 

 iron, and sulphur, the whole being vulcanized. (John D. Prince, 

 Boston, Massachusetts. United States patent No. 1,305,621.) 



Phenolic Condensation Product .\nd Process. A fusible 

 product of para-cresol and a substance containing a mobile methy- 

 lene group. The product fuses at temperature above 115 de- 

 grees C. (Leo H. Bakeland, Vonkers, New York, assignor to 

 General Bakclitc Co., New York City. United Slates patent -Vo. 

 1.306,681.) 



Process for Tre.^ting L.\tex .\nd Product. The process com- 

 prises rendering the nitrogenous matter contained in a mass of 

 latex insoluble, subjecting the mass to vacuum evaporation and 

 adding a vulcanizing agent (Edward Mark Slocum, Medan, 

 Sumatra, Dutch East Indies, assignor to General Rubber Co., 

 New York City. United States patent No. 1,306,838.) 



Method ok \V.\terproofing Fabrics. Textile fabrics and wear- 

 ing apparel are treated with paraflSne wax in conjunction with 

 petrolatum and a selenium-treated Chinese wood oil. (Herbert 

 P. Pearson, assignor to Pearson Products Corporation, both of 

 New York City. United States patent No. 1,307,373.) 



