THE INDIA RUBBER WORLD 



appearance and wearing qualities not only replaces ebonite, but, 

 owing to its extraordinary cheapness and special qualities, may 

 displace ebonite in the market. It may be used for practically 

 every purpose for which ebonite is adapted. ("Electrical Re- 

 view." London. ) 



ANALYSIS OF VULCANIZED RUBBER. 



"T" HE FOLLOWING METHODS for the analysis of vulcanized rub- 

 ■*■ l)€r are by J. A. S. .Morrison in "The India Rubber Jour- 

 nal," June 21, 1919. 



RUBBER RESINS. 



Rasp the sample into small pieces, weigh out four grams, and 

 extract with acetone in a Soxhlet extractor for two days. Dry 

 the extract at 100 degrees C, and weigh. This extract contains 

 rubber resins and free sulphur, the latter being estimated in the 

 extract as described later. Total extract minus free sulphur 

 gives rubber resins. Reserve the residue from the extraction for 

 the determination of the rubber substitutes. 



MINERAL MATTER. 



One or two grams of the original sample is boiled with SO cc. 

 nitrobenzene in a flask fitted with an air reflux condenser ; cool 

 and wash into a 300-cc. tall beaker with a mixture of two vol- 

 umes of sulphuric ether and one volume of ethyl alcohol ; dilute 

 to about 250 cc. with this mi.xture; stir and allow to stand over 

 night to settle. Viscous deposits are due to insufficient ether, and 

 more should be added if these occur. Filter the insoluble matter 

 on a tared filter, dry and weigh. This gives organic matter in- 

 soluble in nitrobenzene plus mineral matter. The contents of 

 the tared filter are washed with warm dilute hydrochloric acid. 

 Wash the acid out with water, dry and weigh. Finally ash the 

 paper and residue and weigh. Ash plus loss due to hydrochloric 

 acid washing gives total mineral matter. The extraction with 

 hydrochloric acid is to extract carbonates as such. 



The difference between the total nitrobenzene residue on the 

 tared filter and the total mineral matter gives the organic mat- 

 ter insoluble in nitrobenzene. Carbon, if used as a filling, will 

 be included in this figure. 



FREE SULPHUR. 



Take acetone extract (rubber resins) in flask, moisten with 

 water and cautiously add 25 cc. fuming nitric acid, cooling the 

 flask in ice. Gently warm and finally digest on steam bath, using 

 a funnel as cover. When action is complete wash into a porce- 

 lain dish with a few cc. of fuming nitric acid, and evaporate off 

 all the acid. All the sulphur is now converted to sulphuric acid. 

 Intimately mix the mass with five grams of a mixture of three 

 parts sodium carbonate and two parts of potassium nitrate, 

 moisten slightly with water and mix well. Cover with a large 

 dish and heat over a low flame till white. Cool and take up 

 with concentrated hydrochloric acid, evaporate to dryness twice 

 to precipitate silica, and finally dissolve in dilute hydrochloric 

 acid, filter and precipitate as barium sulphate. Filter, dry weigh 

 and calculate as free sulphur. 



OXIDIZED OIL RUBBER SUBSTITUTES. 

 The residue from the acetone extraction in the determination 

 of rubber resins is digested with 100 cc. of approximately half 

 normal alcoholic potash for four hours at 60 to 70 degrees C. 

 Pour off through a filter and digest residue twice with warm 

 alcohol. Mix filtrate and alcoholic washings and evaporate 

 nearly all the alcohol. Take up residue in a little cold water, 

 transfer to a separatory funnel, acidify and remove fattj' acids 

 with ether. Evaporate ether extract to dryness and weigh. 

 This gives fatty acids of oxidized oils, and is taken as the per- 

 centage of rubber substitutes. 



VULCANIZED RUBBER. 



This is obtained by subtracting the sum of the other deter- 

 minations from 100. 



TOTAL SULPHUR. 



The method is the same as that described under free sulphur, 

 except that the original rasped sample is used. The difference 

 between total and free sulphur gives combined sulphur, but this 

 is included in vulcanized rubber and seldom separately ex- 

 pressed. 



Ash is often determined by ashing in a porcelain crucible, 

 recarbonating with ammonium carbonate solution, and finally 

 igniting at a gentle heat. The ash is generally lower than total 

 mineral matter because some mineral matters do not recarbonate 

 easily. Nevertheless it serves as a useful check on the figure 

 for mineral matter. 



CHEMICAL PATENTS. 



Drocess of Producing Isoprene. (O. Graul and G. Hanschke. 

 ^ United States patent No. 1,298,929.) 



Vulcanizing Rubber Mixture suitable for repairing punc- 

 tures in tires, consists or crude rubber, one pound ; gasoline, three 

 pints ; litharge or red lead, seven ounces ; lead acetate, two 

 ounces ; sulphide of mercury, seven ounces ; asphalt, three 

 ounces, and sulphur, 2K' to five per cent of the weight of the 

 rubber. (W. T. Hale, Dodge City, Kansas. United States 

 patent No. 1,300,263.) 



Method of Tre-\tin-g Vulc.^nizable Plastics by first apply- 

 ing an internal vacuum, and then vulcanizing under ex- 

 ternal heat and pressure, the vacuum being continued during 

 that portion of the application of the vulcanizing temperature 

 during which vapors or gases are given off by the rubber. 

 (Raymond B. Price, Mishawaka, Indiana, assignor by mesne 

 assignments to The Goodyear's Metallic Rubber Shoe Co., 

 Naugatuck, Connecticut. United States patent No. 1,309,485.') 



Decorated Rubber Articles made by compounding a mass 

 of unvulcanized rubber with a light sensitive material, forming 

 the compound into the article desired, and subjecting the sur- 

 face of the article to light rays conforming with the desired 

 design, and then subjecting the article to heat. (Albert A. 

 Somerville, Flushing, N. Y., assignor to New York Belting & 

 Packing Co., New York City. United States patent No. 

 1.309.703.) 



THE UNITED KINGDOM. 



Devulcanizing Waste Rubber is effected by treatment with a 

 vulcanizing accelerator in the presence of a reagent capable of 

 removing the sulphur as it is liberated. Preferably, uncombined 

 sulphur is first removed; the rubber should be in a finely divided 

 state, for example, in solution ; and no moisture should be present. 

 A temperature of 170 to 180 degrees C. is preferable. Examples 

 of accelerators used are aniline, piperidine and paramido-di- 

 methyl-aniline. (D. Spence, Norwalk. Connecticut, U. S. A. 

 British patent No. 126,397.) 



Surgical Dressings made up in the form of candles with 

 wicks so that the material is readily melted and applied. The 

 candles are coated with paraffined paper or with a solution of 

 lacquer, wax, resin, cellulose acetate. Suitable additions to the 

 paraffine are rubber or latex, antiseptics or medicaments. (P. 

 Ehrhardt, 95 rue Jouffroy, Paris. British patent No. 126,501.) 



Vulcanization Accelerators. Double compounds of nitroso- 

 dimethyl-aniline or its homologs with aromatic bases are used 

 a.i accelerators in the vulcanization of rubber. Compounds con- 

 taining two molecules of nitroso-dimethyl-aniline and one mole- 

 cule of aniline, dimethyl-aniline, ortho-toluidine, diphenyl- 

 amine, or alpha-naphthylamine are given by way of example. 

 (J. F. B. van Hassett, 92 Almondestraat, Rotterdam. British 

 patent No. 126,606.) 



Chlorinating India Rubber. In the production of a substance 

 for use as a substitute for celluloid, leather, or the like, by 



