266 



THE INDIA RUBBER WORLD 



February 1, 1917. 



dilated amiiuiit foiiiKl. ami rccuri 

 matter." 



TARKY 1-OREIGN MATTER. 

 If the compound is light in color, tar, pitch and asphalt shall 

 he considered absent. If the compound is dark or black in color 

 the residue after the acetone extract determination above, without 

 removing the acetone, and before the alcoholic potash is made, 

 is extracted with chloroform for four hours in the same manner 

 and by the same procedure as for the acetone extraction. If the 

 extract is very dark in color, or the residue is tarry, from its 

 calculated amount shall be subtracted 3 per cent of the weight of 

 vulcanized rubber gum, as determined below, and the balance 

 recorded as "tarry foreign matter." 



PRECAUTIONS. 

 When the chloroform extraction is made the day after the 

 acetone extraction, the rubber residue shall be covered with ace- 

 tone over night. When the alcoholic potash extraction is made 

 the day after either the acetone extraction or the chloroform ex- 

 traction, the dried rubber residue shall be covered with the alco- 

 holic potash over night. 



CARBONACEOUS FOREIGN MATTER. 



Heat about one gram sample with 30 cc. of concentrated nitric 

 acid and 15 cc. water. A lilack insoluble residue indicates the 

 presence of carbon, as lampblack, graphite, etc. Examine the 

 ground rubber under the microscope and observe the residue of 

 fillers in the mineral fillers determination. If fibers or carbon are 

 seen, except as a trace, proceed as follows : 



The crucible containing the fillers is washed with hot dilute 

 hydrochloric acid and hot water to decompose carbonates and 

 sulphides, dried to constant weight at 105 to 110 degrees C, 

 desiccating until cool. The crucible is then ignited to constant 

 w-eight and the loss calculated and recorded as "carbonaceous 

 foreign matter," and shall be subtracted from the percentage of 

 "mineral fillers" recorded above. 



SPECIFIC GRAVITY. 



Make the deterinination on a strip or strips not less than five 

 grams weight. Weigh to one milligram in air, then, thoroughly 

 wet with water, pressing and squeezing, with the fingers under 

 water, to remove bubbles or films of air. Weigh to one milli- 

 gram in water at 20 degrees C. (taken as 1.00), calculate to 0.001 

 and record as "specific gravity." 



RATIOS. 



Free sulphur ami organic acetone extract are separately cal- 

 culated and recorded as percentages by weight of vulcanized 

 rubber gum present. 



tlie balance as "oily foreign Pricstnall Knad, llcaton Mersey, England. British patent No. 



101,819.1 



CHEMICAL PATENTS 



THE UNITED STATES. 



Phenolic Condensation Product. A coating composition 

 containing a phenolic condensation product and a cellulose ester, 

 in conjunction with tetrachlorethane. [Whitney B. Jones, Perth 

 Amboy, New Jersey, assignor to General Bakelite Co., New York 

 City. United States patent No. 1,209,165.] 



Dental Rubber Composition. Dental plates made of finely 

 ground vulcanized rubber compounded with raw rubber. The 

 object is to neutralize the expansion of the one by the other 

 during vulcanization. [S. G. Supplee and C. J. R. Engstrom. 

 United States patent No. 1.204.609.1 



THE UNITED KINGDOM. 



Vulc.\nization .'\ge.\t. Nitrosophenols or their homologues, 

 such as nitrosocresols or nitrosoxylenols, are used for facili- 

 tating the vulcanization of natural or artificial caoutchouc or 

 caoutchouc-like substances. In an example, ten parts of sulphur 

 and one part of nitrosophenol are used for vulcanizing 100 parts 

 of rubber at a temperature of 135-145 degrees C. [S. J. Peachey, 



Ce.mlnting Ebonite. Parts of ebonite articles are cemented 

 together by means of a solution of celluloid in amylacetate or 

 other solvent. [C. A. Vandervell, Warple Way, Acton Vale, 

 Middlesex, England. British patent No. 12,075 (1915).] 



Fibrous Sheet. Sheet material from fibers arranged sub- 

 stantially parallel is impregnated by a binding material; im- 

 pregnation done in a vacuum. Multiple-ply stock, with cross 

 layers of fibers, may be made from such inaterial ; and in that 

 state is applicable to the manufacture of tires, hose, matting, 

 lielting, covers, heels and soles. [Rubber Regenerating Co., New 

 York City. British patent No. 101,318.] 



SWITZERLAND. 



Elastic Product. A composition of gas tar, rubber, ordinary 

 cement and mineral filling. The gas tar minus some of its 

 oil is mixed with rubber dissolved in a solvent composed of 

 benzene and carbon disulphide. This mass is liquified by heat, 

 and cement and mineral filling added. The resulting mass is 

 mixed and molded hot. [C. A. C. de Caudemberg. Swiss patent 

 No. 73260, (Sept. 16, 1916).] 



LABORATORY APPARATUS. 



instrument eor measuring watekproofing effect on fabkics. 



AN instrument recently invented for measuring the imper- 

 meability of waterproofing on cloth has been described in 

 the "Journal of the Society of Dyers and Colorists." The method 



of measurement is based 

 on the determination of 

 the number of hammer 

 strokes upon the cloth 

 before the water perco- 

 lates through, the cloth 

 being pressed upwards 

 by a column of water. 

 The instrument consists 

 of a copper cylindrical 

 box A on the top of 

 which is fixed by a ring, 

 B, tightened with a screw C, the cloth to be tested. The pres- 

 sure of water against the cloth is regulated by the movement 

 of the wooden cylinder D in the glass reservoir E, on which 

 the height of the water is marked in centimeters. 



When the water is five centimeters high the hammer F is 

 dropped. The hammer has a w-eight of three grams, which 

 may be increased by a movable weight G. After the first stroke 

 the water is raised one centimeter, and after every subsequent 

 stroke it is raised again. The number of strokes required before 

 the water appears on the surface of the cloth shows the degree 

 of impermeability. 



SULPHURIC acid IN 1916. 



Market conditions throughout the country are reported to have 

 Iieen on the whole better than in 1915. despite the somewhat 

 higher value of the product. Reclaimers of rubber will be in- 

 terested to know that according to reliable estimates by the 

 United States Geological Survey the output of acids of strengths 

 of 60 and 66 degrees amounted to nearly 950,000 tons, or prac- 

 tically the same as in 1915. The total estimated production of 

 sulphuric acid, however, of strengths of 50, 60 and 66 degrees was 

 4,475,000 tons as expressed in terms of 50-degree acid, represent- 

 ing an increase of 600,000 tons or more than 15 per cent. The 

 most notable feature in the sulphuric acid industry was the 

 enormous increase in the production of acids of strengths greater 

 than 66 degrees. The estimate shows a production of over a 

 million tons as against less than 200,000 tons in 1915. 



