December 1, 1918.] 



THE INDIA RUBBER WORLD 



cc. one in ten hydrochloric per 100 cc. of ten per cent latex to 

 ten cc, one in ten hydrochloric per 100 cc. ten per cent latex. 



A similarly located gap over which no coagulation, or only very 

 incomplete coagulation occurs, is noticed in the case of nitric 

 ac;d. 



CONCLUSION. 



The coagulation of cow's milk under the influence of rennin 

 offers a much closer analogy to the coagulation of Hevea latex 

 than does the clotting of milk by added acids or natural souring, 

 and the salient agency in latex coagulation is probably enzymic. 



The initial formation of the clot in fresh latex allowed to un- 

 dergo natural change is probably due to enzymic action and the 

 same agency, activated by acids, is probably responsible for 

 acetic coagulation. Bacterial action is viewed, in regard to the 

 occurrence of natural coagulation in latex, as a secondary factor 

 only. 



In addition to coagulation taking place ordinarily under the 

 influence of an enzyme, there may occur under special conditions 

 coagulation of other types — viz., the delayed coagulation in latex 

 which has been subjected to sterilization, due to the ultimate 

 putrefactive decomposition of the latex ; the non-coherent coagu- 

 lation produced by heat or by protein precipitants, particularly by 

 tannic acid, and not improperly the coagulation produced by 

 hydrochloric and nitric acids on the far side of the "gap" which 

 is associated with the addition of increasing quantities of these 

 acids to latex. 



Very much remains for investigation in connection with latex 

 coagulation. It is believed that at the present stage the enzymic 

 hypothesis of coagulation affords the best explanation of the facts. 



OYOGALITH, THE FRENCH GALALITH. 



A French manufacturing company, called the Oyonnaxian Co., 

 located at Oyonnax, a well-known French industrial center, has 

 perfected a new non-inflammable product from casein similar but 

 superior to German galalith. This product is designated as 

 oyogalith and is sold under that name, manufactured into such 

 articles as buttons, buckles, rings, combs, knife handles, etc. This 

 new material is cited by "Le Caoutchouc et la Gutta-Percha" as 

 one of the many successful substitutes for German-made material 

 which has lieen developed during the war. 



WATERPROOFING BRAIDED CORD. 



Cord can be waterproofed either before or after braiding. 

 Various methods of proofing, says the "Textile World Record," 

 can be used in either case. For example, cotton yarn may be 

 proofed in a solution of 30 pounds of alum in 50 gallons of 

 water to which 30 pounds of sugar of lead has been added. The 

 yarn must be soaked for two hours, after which it is lifted 

 out of the solution and drained, then passed through a weak 

 soap solution, which results in a deposit of an aluminate of the 

 soap fat in the yarn. Or one can proof yarn in the following 

 solution : dissolve SO pounds of alum in 500 pounds of water, 

 soak SO pounds of glue in 10 gallons of water overnight, heat 

 to boiling in the morning and when solution is complete stir 

 in 2H pounds of tannic acid and 1 pound of silicate of soda, 

 add the entire quantity to the alum solution, mix thoroughly 

 and cool to about 170 degrees P., immerse the yarn till satur- 

 ated, squeeze and dry. 



A mixture of rubber and paraffin wax waterproofs w^ell ; it 

 also insulates. Melt S pounds of paraffin wax in an iron pot, 

 add 1'4 pounds of scrap rubber, heat until rubber is dissolved, 

 cool and permit solidification, then cut into cubes for use. Weigh 

 the yarn or other material to be proofed in a dry state; for 

 every eight pounds allow one gallon of benzine in which three 

 ounces of the paraffin rubber mixture has been dissolved. Soak 

 the yarn in the solution, which will soon be soaked up, then let 

 the benzine evaporate ; a waterproof deposit will be left on the 

 yarn. If cable has been so treated, a finish may be given by 



passing it between heated grooved rollers, cable can be rubbed 

 by paraffin wax before going through the rollers. Finally, 

 cable can also be waterproofed by drawing it through melted 

 paraffin in a long shallow pan, the cable being kept below the 

 surface by guide rollers ; upon leaving the pan of wax it is 

 drawn between wipers, then through grooved finishing rollers 

 and coiled. 



DEPOLYMERIZATION OF RAW RUBBER. 

 K. Kawakami presents his views on the depolymerization of 

 raw rubber in the "Journal of Chemical Industry," Tokio, Japan, 

 of which the following abstract is made by the "Journal of the 

 Society of Chemical Industry," London, August 31, 1918. The 

 author criticizes and points out inaccuracies in the experiments 

 by Takenchi, but agrees with the general proposition that viscos- 

 ity measurements may be of value in controlling the processes of 

 manufacture. The viscosity is not an absolute function of de- 

 polymerization, since it is affected also by the non-caoutchoue 

 matters, namely, proteins and rubber resins, which will not 

 change in the same proportion as the caoutchouc. The degree 

 of variation of the acetone extract during mastication falls with- 

 in the limits of experimental error. The viscosity of raw rub- 

 ber cannot be used as a sole measure of valuation, because there 

 are several factors of value which have nothing to do with the 

 viscosity of the solution : for instance, the amount of impurities 

 and loss in washing, also the physical and chemical properties 

 of the vulcanized products. The proper periods of mastication 

 obtained from Takenchi's curves, on the basis of an absolute 

 viscosity of 0.1 in the rubber solution, work out at 40 minutes 

 for plantation and 80 to 90 minutes for Brazilian Hevea. but 

 these periods appear far too long from a technical point of view. 



MOISTURE IN RAW RUBBER. 



The following abstract is from a paper by G. Stafford Whitby, 

 M. Sc, A. R. C. S. in the "Journal of the Society of Chemical 

 fndustry," August 31, 1918: 



The present paper records observations made under actual 

 tropical conditions on the variation of the water-content of raw 

 rubber and the relation of this quantity to the humidity of the 

 atmosphere, the form of the rubber, and the presence of serum 

 solids. The observations were confined to rubber produced by 

 acetic acid coagulation from the latex of Hevea Brasiliensis. 

 The moisture content of both crepe and sheet rubber was ob- 

 served to exhibit a diurnal change, being on a normal day in the 

 Eastern tropics, very markedly higher in the early morning than 

 in the late afternoon. There is a general parallelism between 

 the water-content of crepe and the degree of humidity of the 

 atmosphere. 



The course of drying samples of latex crepe from shortly 

 after preparation to the time when they were dry showed that 

 after the percentage of water had fallen to about one per cent 

 the samples showed a negative state of drying between sunset to 

 sunrise, the most humid part of the day, the rate of drying being 

 influenced by variations in the degree of humidity of the at- 

 mosphere. Sheet rubber was found to be less sensitive than 

 crepe, as regards its moisture-content, to changes in the degree 

 of humidity of the surrounding atmosphere. It exhibited 

 smaller variations than crepe in the percentage of water present 

 at different times retaining a higher percentage of water in the 

 middle of a hot, dry day, and absorbing less moisture over night. 

 It is probable that the higher moisture-retaining capacity which 

 sheet samples show under usual commercial conditions, depends 

 upon the fact that the serum solids are removed from the coag- 

 ulum less completely in the preparation of sheet (ban in the 

 preparation of crepes. 



The greater readiness with which crepe, as compared with 

 sheet, increases its water-content in a humid atmosphere may 

 probably be regarded as due to the much greater surface which 



