36 



THE INDIA RUBBER WORLD 



[October 1, 1913. 



described and illustrated models are so designed as to combine 

 service and style effect at very low cost ; while for those who 

 dislike to be deprived of their morning ride or tramp, outfits 

 as here mentioned, which afford warmth and protection from 

 the rain and at the same time justify no adverse criticism as 



to fashionable construction, will be welcome 



wardrobe additions. 



RAINCOATS FOR DOLLS. 

 In addition to supiilyiut; rubber garments 

 and caps and hats for actual people in real 

 life, some manufacturers have provided 

 comprehensive lines of rubberized garments 

 for the doll family. The Stern Specialty 

 Co., of New York, London and other places, 

 for instance, carries fifteen different styles 

 of rubberized coats and cloaks for small 

 people made of china and wax. These 

 garments are made both in silk and cotton. 

 The accompanying illustration shows a 

 handsome young doll all ready for an auto- 

 mobile ride, in her rubberized coat and a 

 " pair of goggles. 

 It has not yet come to the notice of the editor of this column 

 whether a full line of mackintoshes has been made for the 

 dog family, l)ut it is not an unusual sight in inclement weather 

 to see bulldogs and other dogs of high degree moving de- 

 corously along the city avenues protected by rubber blankets, 

 lined with wool to keep the animal warm while the rubber keeps 

 him dry. 



RESULTS OF VARIOUS COAGULANTS 



COAGULATION has been defined as the formation of 

 liquid latex into a mass, thus giving birth to a substance 

 of extremely "nervy" and elastic character. 



As M. G. Vernet remarks, in the "Revue Internationale," 

 two principal theories have been propounded with respect to 

 this process. On the one hand, it has been maintained that 

 the thickening of the latex is only caused by the coagulation 

 of the albuminoids, in the same way as globules of blood are 

 agglutinated by the coagulation of the albumen present. 



M. Victor Henri, on the other hand, entirely rejects this 

 view. Assimilating the coagulation of late.x with the precipita- 

 tion of colloids, he considers that it is chiefly produced under 

 the influence of electrolytic agents; that is to say, of salts, 

 acids and compounds acting in that way. 



In M. Vernet's opinion, the views of M. Henri are likely 

 to make rapid progress among students of coagulation. They 

 lead him to believe that the best qualities of rubber can be 

 obtained by the use of salts and acids as electrolytic agents. 

 He considers, however, that coagulation may be induced at 

 the same time or separately by various other factors, which 

 he treats in detail as follows: 



DESSICATION. 



The dessication, or evaporation of tlie water of the latex, 

 causes the formation of a dry extract; but this dry extract 

 has no longer the property of being completely soluble in 

 water, so as to again form the original latex. The globules 

 of rubber, in particular, are agglomerated, and it can thus be 

 said that coagulation takes place by reason of the progressive 

 approximation of the globules. 



In practice, this method of coagulation is not willingly 

 used in the case of Hevea latex, more or less diluted with 

 water, and reaching the factory in a liquid state. This opera- 

 tion would be too expensive for the rapid cold evaporation 

 of all the water contained in the latex. 



HEAT. 



Heat induces coagulation of latex only in an acid medium. 



In a neutral or alkaline medium, the boiling does not lead to 

 the combination of the rubber globules, nor to the coagulation 

 of the albuminoids in the latex; but, if the liquid is acidified, 

 coagulation takes place. The more acid the latex is, the less 

 need is there to raise the temperature to produce its 

 coagulation. 



Notwithstanding what may have been said, pure latex is 

 always acid even at the time of flowing from the tree, and it 

 may thus be directly coagulated by heat. It thickens at 65 

 degs. C. (149 degs. F.) and coagulates at 70 degs. C. (158 

 degs. F.). This system is, however, but little used. 



SALTS. 



It may be said that at the present time salts are not used 

 for producing the coagulation of Hevca late.x. trials made in 

 Java and Ceylon having been unsatisfactory. It has been 

 found that the quantity of the reagents which requires to be 

 used with salts exceeds the weight of organic acids needed 

 for the coagulation of the latex. 



M. Henri has brought forward this question again, urging 

 that double and triple salts of metals are excellent coagulants 

 of rubber. He specially mentions salts of calcium, magne- 

 sium, zinc, lead and aluminium, which, in an acid medium, 

 produce an electrolytic effect on the grouping of the globules. 



Difficulties have attended the use of salts without the addi- 

 tion of acid to the latex to produce coagulation, but M. 

 Vernet considers it possible that the judicious choice of re- 

 agents, and the extent to which they are used with ordinary 

 latex not freed from acid, may lead to very satisfactory results. 



ACIDS. 

 It was at first thought that the action of acids upon 

 coagulation was only due to the insolubility of the albu- 

 minoids, containing the globules of rubber. M. Henri has 

 since shown that with latex freed from its salts or crys- 

 talloids, acids do not produce complete coagulation, but only 

 the agglutination of the rubber. In ordinary Hevea latex all 

 acids produce coagulation, but the proportions of organic 

 acids needed for that result are larger than is the case with 

 mineral acids. The former are, however, preferred, on ac- 

 count of the corrosive action of the latter (such as that of 

 sulphuric acid, hydrochloric acid, or azotic acid) upon the 

 impurities which remain in the mass, as well as upon the 

 metallic portions of the plantation factory plants. 



USE OF SALTS AND ACIDS TOGETHER. 

 Finally, M. Vernet advocates the combined use in coagula- 

 tion of salts and acids. To use his own words, "Like salts, 

 acids employed alone do not produce good results, but remark- 

 able effects can be obtained by the simultaneous use of both." 



INDIA WANTS AMERICAN ASBESTOS. 



The United States consul at one of the large centers in India 

 sends in the following information (Consular report No. 11,457) 

 regarding the demand in that country for American made as- 

 bestos sheets : 



"A business firm in India would like to ascertain if any Amer- 

 ican firms make corrugated asbestos sheets for roofing. This 

 firm knows at present of these sheets being made only in Can- 

 ada, and would like to secure competitive quotations if possible 

 from the United States and act as agent for any American con- 

 cern which may turn out a reliable and low-priced article. It 

 is thought that India presents a good field for corrugated as- 

 bestos sheets for roofing, as these would prove cool and light 

 for the hot Indian climate." 



Should be on every rubber man's desk — Crude Rubber and 

 Compounding Ingredients; Rubber Country of the Amazon; 

 Rublier Trade Directory of the World. 



