388 



THE INDIA RUBBER WORLD 



[April 1, 1917. 



is, therefore, confronted with the choice of either placing a limit 

 on the total sulphur or giving up the attempt to exclude shoddy 

 by sulphur limitation. Option is, therefore, given to the pur- 

 chaser to insert or omit the limit on total sulphur. Such inser- 

 tion will at times exclude reclaimed rubber and the committee 

 believes it possible to make a suitable compound witli this limita- 

 tion. The committee thinks that a sulphur Hmit positively ex- 

 cluding reclaimed rubber, would place too great a hardship, in 

 other ways, on the manufacturers. Where the specification is 

 used with no total sulphur limit, the use of many kinds of, or 

 much reclaimed rubber, will be guarded against by the limits of 

 the various components of the acetone extract. When the limita- 

 tion on total sulphur is omitted, sulphur-bearing fillers, which 

 possess certain advantages, may be used. 



This specification should be supplemented by appropriate elas- 

 ticity anci tensile strength tests, in order to add to the assurance 

 that good rubber has been used and that the vulcanization process 

 has been properly carried out; also by appropriate electric stress 

 and resistance tests, to assure proper insulating qualities and 

 homogeneity of structure. The exact vahie of the limits for 

 these tests will depend upon the use to whicii the material is to 

 be put. 



IMPORTANT SPECIFIC.VTIONS CONTAINING THE JOINT RUBBER 



INSULATION COMMITTEE'S CHEMICAL CLAUSES OR 



ANALYTICAL PROCEDURE. 



American Electric Railway (Engineering) Association: 

 Standard Specification for Rubber Insulated Wire and Cable. 



American Societv for Testing Materials: Proposed specifi- 

 cations for Insulated Wire and Cable; 30 per cent Hcvca Rubber. 



Association of Railway Electrical Engineers: Standard 

 Specifications for Wire and Cable. 



Interborough Rapid Transit Co., Motive Power Department, 

 New York : Specification No. 2. 



New York Central Railroad Co., Electrical Deiartment: 

 Specification No. 300. 



Panama Canal : Office of General Purchasing Agent. Circu- 

 lar No. 1,038. 



Signal Corps, U. S. Army: General Specification No. 581-.-\, 

 etc. 



ALUMINUM NAPHTHENATES. 



The properties and method of obtaining aluminum naphthe- 

 nate is described by G. Nothe in "Le Caoutchouc & La Gutta 

 Percha" (November, 1916). Pure naphthenic acid from Baku 

 petroleum, when treated with alumina, yields aluminum 

 naphthenate, which, according to the method employed, may be 

 a powder or a colloidal mass, very elastic and plastic, not 

 unlike factis. The materia! is used in rubber mixings and 

 vulcanizes readily. German pneumatic tire manufacturers 

 largely use such a naphthenate manufactured by the E. de 

 Haen Co. Aluminum naphthenate is nearly insoluble in 

 acetone, and gives with chlorides of hydrocarbons very viscous 

 colloidal solutions forming transparent films of great strength. 

 By using a sufficient quantity of solvent the gel which first 

 forms, gives, on gentle heating, faintly yellowish fluid solu- 

 tions, miscible in all proportions with cellulose acetate produc- 

 ing strong films. The Germans have utilized this material in 

 large quantities as a substitute for rubber, mixed with reclaimed 

 rubber in the manufacture of pneumatic tires during the war. 



CEARA RUBBER FROM NIGERIA. 



Two samples of Ceara rubber are reported by the Bulletin 

 of the Imperial Institute (1916, volume 14, pages 382-384>. 

 These samples were rough sheets prepared from latex tapped 

 by the Lewa system from trees growing in the government 

 plantation at Ankpa, Bassa, Northern Provinces, Nigeria. The 

 physical properties of the samples were satisfactory and the 

 analytical results showed loss on washing: 5.3 and 8.0 per 

 cent on original sample ; and caoutchouc, 83.1 and 84.7 ; resins, 

 5.3 and 6.3; protein, 9.9 and 7.7; ash, 1.7 and 1.3 on the dry- 



washed rubber. A comparison of the second sample with 

 plantation Para sheet, with regard to their behavior on vul- 

 canization gave the following results: Time of cure at 50 pounds 

 steam pressure, Ceara 50 minutes, Para sheet 70 minutes; ten- 

 sile strength 2,330, 2,300-2,400 pounds per square inch; elonga- 

 tion 847-875 per cent. The ages of the trees from which the 

 two samples were obtained were, respectively, three years and 

 three to four years, their average girth being 15 inches and 

 18 to 20 inches at three feet from the ground. [Journal Society 

 of Chemical Industry, January 31, 1916.] 



FREE AND COMBINED SULPHUR IN VULCANIZED RUBBER. 



B. J. ]':aton and F. W. F. Day in "The Journal of the Society 

 of Chemical Industry" (January IS, 1917), recount their research 

 on a "Preliminary Investigation on the Estimation of Free and 

 Combined Sulphur in Vulcanized Rubber, and the Rate of Com- 

 bination of Sulphur with Different Types of Plantation Para 

 Rubber." They found it necessary to devise a special method 

 for sulphur determination in vulcanized rubber. After pro- 

 tracted acetone extraction, combustion of the extracted rubber 

 is effected in oxygen under special conditions. The authors 

 state that the combustion method described would be inadmissible 

 for estimating sulphur in vulcanized mineral mixings, although 

 it enables them to balance the free sulphur and the combined 

 sulphur against the total sulphur and against the original 

 sulphur put into the mixing investigated. This mixing was 90 

 per cent rubber and 10 per cent sulphur. Three types of rub- 

 ber were investigated, namely slab, sheet and crepe. All 

 of these samples were prepared from similar latex and under 

 identical conditions except as to machining. It was concluded 

 that "the percentage of combined sulphur at the optimum time 

 of cure is practically the same for all three types, and this per- 

 ccnta.ee of sulphur at the optimum time of cure is always about 

 4 to 4.5 per cent, calculated on the mixing. Whether this will 

 be so for all samples remains to be seen." 



CHEMICAL PATENTS. 



Insulating Composition. Phenol condensation compound 

 and solvent. Leo H. Bakeland, Yonkers, New York, assignor 

 to General Bakelite Co., New York City. [United States patents 

 Nos. 1,216,265 and 1.216,266.] 



Rubber Composition and Process. The process of making 

 rubber compositions which comprises working together rubber, 

 a dry sulphite waste liquor preparation, a composition of blown 

 petroleum and asphalt, and other body-giving components. 

 [Michael F. Coughlin,' Boston, Massachusetts, assignor to Ameri- 

 can Gum Products Co., Covington, Virginia. United States 

 patent No. 1,217,157.] 



Shoe Filler Composition, h filling material for shoes com- 

 prising a solution of rubber in a solvent, comminuted cork, car- 

 bon tetrachloride, and sulphur, the proportions being such that 

 the resulting mixture is plastic and adapted to vulcanize quickly 

 when spread on the bottom of the insole of a shoe. [.-Vdam H. 

 Prenzel, Halifax, Pennsjdvania, assignor to United Shoe Ma- 

 chinery Co., Paterson, New Jersey. United States patent No. 

 1,217,214.] 



Caoutchouc-Like Material. A caoutchouc-like body result- 

 ing from the reaction caused by adding dichloride of sulphur to a 

 mixture containing a ketone capable of yielding isoprene and 

 caoutchouc. [Herman Stern, Munich, Germany, United States 

 patent No. 1,218,713.] 



Method of Impregn.\ting Fabrics. Fabrics are treated with a 

 preparation made by mixing rubber, sulplionated castor oil and 

 sulphur. The treated fabric is dried and finally vulcanized. 

 [Lauritz Peterson-Hviid, Copenhagen, Denmark. United States 

 patent No. 1,219,349.] 



