February 1, 1915.] 



THE INDIA RUBBER WORLD 



267 



Chemical Industry," 1914, p. 289, and Chi [ndia Ri bber World, 

 August, l'»14, p. 600, have very thoroughly treated this subject. 

 They conclude that acid and salts are both necessary, but there 

 an spme --alts in the latex. 



M. X'eniii i I hi [ndia Rubber World, October, 1913, p. 14) in 

 discussing this subject says there are difficulties in using both 

 acids and salts fur coagulation, but advises their use B.J. Eaton 

 says that o.l gr. of acetic acid to 100 ( C oi latex is sufficient 

 ("Journal oi Society of Chemical Industry," I "J 13, p. 1097). 

 i l'.en\ has received British patent X". 16,728, of 1913, for 



Coagulating latex with one-tenth per cent, of 5 per cent, solu- 

 tion of sulphurous acid. S. C. Davidson has received I'.ritish 

 patents No 13,438 and No. 20,183 of 1913, and No. 764 of 1914 

 for coagulating by the use of creosote (The India Rubber 

 Wcrld, December, 1914). Byrne has applied to the German 

 patent office for patent on using wood vinegar for this purpose 



Schidrowitz and Goldberg ("India Rubber Journal," Vol. 44. 

 p. 1147) after experimenting verj thoroughly find that the less 

 acid used in coagulating the better the quality of the rubber. 

 F. kavc has shown ("India Rubber Journal." 1913, p. 1297) 

 thai the acid combines with proteins in vulcanization. 



The Rubber Planters' Association ("Planters' Chronicle," 

 August 25, p. 628) has recently had extensive experiments made 

 on the production of acetic acid fur coagulating and investigated 

 other substances. It is claimed that the slightest trace of copper 

 in the acid is fatal to coagulation work, as it produces a slimy 

 coagulation and a worthless product, and great care is exercised 

 to obtain acid free of copper. Toddy vinegar, bi-sulphate (not 

 sulphite) of soda, formic and lactic acid are recommended, and 

 if unobtainable, sulphuric acid is allowable. Alum is said to be 

 much used by the natives for coagulating. Eichelbaum received 

 German [latent No. 256,904 and addition No. 254,196 for preserv- 

 ing latex with sulpho-silicate compounds and formaldehyde and 

 later for using hydrosulphites. 



( To BE CONTINUED.) 



THE ANALYSIS OF MATERIALS USED FOR ELEC- 

 TRICAL INSULATING PURPOSES. 



THE criticism of the report of the Analytical Committee of 

 the American Chemical Society, in connection with its 

 work in analyzing materials used for electrical insulating pur- 

 poses, by the Joint Rubber Insulation Committee, elicited the fol- 

 lowing reply from the first named body, which we reprint in 

 full from the "Journal of Industrial and Engineering Chemistry," 

 December. 1914': 



"From the reply of the Joint Rubber Insulation Committee, 

 this journal. 6, 515, it is evident that some discussion of the 

 results as published in this journal. 6, 514, is necessary to pre- 

 vent any misunderstanding as to their bearing. Since this re- 

 pl> appeared it was impossible to hold a meeting of the Analyti- 

 cal Committee until this date. 



"In presenting the results of their work, the Analytical Com- 

 mittee voted to confine their published report to the facts 

 brought out by their analysis and omit all discussions, as a pub- 

 lication of these discussions in full would have occupied more 

 space than this committee could reasonably have asked for and 

 it was by no means certain how much of it would be of general 

 interest. 



"The three compounds selected for analysis were designed to 

 test the accuracy of the methods for analysis of the Acetone 

 Extract as affected by the presence or absence of the two hy- 

 drocarbons used in commercial practice. The amount of rubber 

 and the fillers were varied only slightly to avoid the influence 

 of extraneous factors on the results. The selection of fillers 

 and the respective proportions were designed to fall within the 

 limits prescribed by the 1913 Railway Signal Association's- specifi- 

 cation for 30 per cent, fine 'Para insulation, as this was eon-:. 

 ■ 'ui i id 



to bi hi most important type of material to which the methods 

 of the Joint Rubber Insulation Committee were likely to be 

 immediately applied. The methods of the Joint Rubber In- 

 sulation Committee were intended to be applicable to the analy- 

 sis of just such compounds. Therefore, if the errors have been 

 magnified due to the constituents, the methods should be re- 

 t ised to meel such conditions. 



"The Analytical l ommittee, befi ri issuing its report, took 

 into consideration the discrepancies of analyst Xo. 3 under 

 waxj hydrocarbon, which in all probability were due to the 

 solution of alcoholii potash used. They also took into con- 

 sideration the results of No. 4. under free sulphur, which were 

 obtained by the use of a different type of extractor, for com- 

 parative purposes. Inasmuch as no conclusions drawn from 

 . ithi i of these results were adverse to the methods of the Joint 

 Rubber Insulation I ommittee, no exception was made to the 

 decision of the committee to publish only the results and con- 

 clusions. 



"These discrepancies and the reasons for the same were brought 

 to the attention of the Rubber Section at the Cincinnati meeting 

 and were fully discussed at that time. Two members of the 

 Joint Rubber Insulation Committee, who were instrumental in 

 drawing up the comments printed in this journal, 6, 515, were 

 present at this meeting and were fully acquainted with the facts. 



"A clerical error which appeared in the published report 

 should be corrected as follows; I ndcr Sample A. Analyst I: 



11/20 — Total wax} hydrocarbons should read 2.14 per cent. 



11/21 — Total waxy hydrocarbons should read 2.55 per cent. 



"Referring to the comments on the work of Analyst No. 2, 

 the Joint Rubber Insulation Committee state: 'The results 

 indicate that the Acetone Extraction was not properly made.' 

 i omparison of the results of Analyst Xo. 2 with those of 

 1, 4 and 5. which are taken as a standard for comparison, does 

 not substantiate this statement, as these results are consistent 

 with Xos. 1, 4 and 5 and the duplicate results are particularly 

 consistent; furthermore, the analyst states that the Acetone Ex- 

 traction was made absolutely in accordance with the procedure. 



"The fact that the averages of a large number of determinations 

 are 'about what we would expect from this compound' proves 

 only that positive and negative errors are equally probable and 

 does not substantiate the claim that the determination of saponi- 

 fiable extracts by this method will give accurate results, since 

 the individual results show that the probable error of a single 

 determination is large. 



"This procedure is given as a method for 30 per cent. Hevea 

 rubbers, therefore the Analytical Committee was justified in 

 making its first investigation on fine Para." 

 E. W. Boughton, W. A. Ducca, G. II. Savage, 

 J. B. Tuttle. P. II. Walker, D. W. Whipple. Chairman, 



114 Liberty street, Xew York City, November 16, 1914. 



BISULPHITE NOT BISULPHIDE. 



In reporting the remarks made by Mr. Henry P. Stevens at the 

 International Congress of Tropical Agriculture, in the November 

 number of The India Rubber World, the speaker was made to 

 say that he used small quantities of sodium bisulphide in the 

 manufacture of pale crepe plantation rubber. This was an error; 

 the chemical used by Mr. Stevens was bisulphite of sodium. 



The introduction of sodium bisulphite as an antiseptic in the 

 treatment of rubber latex in the East was due to Mr. Sidney 

 Morgan, the resident chemist of the Rubber Growers' Associa- 

 tion Malaya Research Fund. Samples so prepared were care- 

 fully tested, and the use of this substance has now become prac- 

 tically universal in the preparation of pale crepe rubber. 

 — 



Announcement has been made by steamship lines operating 

 to South Africa of a reduction in the surcharge on freight to 

 15 i>er cent., the old rate having been 20 per cent. 



i , 



