162 



679. RUBBER PREPARATION AND CASTILLOA 



RUBBER. 



L\ the Indian Rubber World of October 1st. 1900, I ventured to 

 publish a critique of the articles previously published by Messrs. 

 Biffen and Parkin in the Annals of Botany under the title of "Latex 

 and its Functions." 



The chief point to which exception was taken was the statement, 

 — also included in paper read before British Association at Dover in 

 1899. That " coagulation is now known to be brought about by the 

 " proteids of the latex passing from a soluble to an insoluble state:' 

 "Experimental evidence points to the proteid in question being 

 "alkali-albumen rather them ordinary albumen. It has previously 

 " been called albumen." 



It Avas said moreover that the coagulation ot the albumenoids of 

 the Latex was necessary tor the "coagulation" of the Rubber globules. 



In our remarks it was stated that the aggregation or "coagula- 

 tion" of the Rubber particles or globules of Rubber was independent 

 of the coagulation of the albumenoids, as they could be aggregated, 

 together, or coagulated quite as easily, if the albumenoids were 

 removed, as in their presence. 



In my paper I also showed that if the albumenoid liquors were 

 drained off the resulting Rubber would be of much finer quality, and 

 that the albumenoid matter could be easily removed in the case of 

 castilloa latex by the simple process of creaming. 



This criticism was answered by Mr. Parkin in a communication 

 to the India Rubber World, of January 1901, in which he still 

 appeared to insist upon his original point of view, namely, that the 

 clotting or coalescence of the Rubber globules was contingent upon 

 the coagulation of albumen. 



Some time has now passed and the subject has again received 

 attention at the hands of Dr. O. Weber of India Rubber Journal, 

 whose articles on the subject treat of the line of practice which 

 should be adopted. It is gratifying to note that he advocates 

 the same methods as those described in our criticism of Mr. Parkin's 

 work. 



Dr. Weber treats the question by describing the fact that 

 the coagulation of albumenoids will take place, and that- in Rub- 

 ber obtained by such a process, there is sure to be a very large pro- 

 portion of resinous matter: while when prepared alter the Latex is 

 rid of the albumenoids a finer quality of material is obtained. 



In his article Dr. Weber quotes our statement that 14 ounces of 

 rubber was obtained from a single tree, while at same time estimating 

 elsewhere that from two to six pounds could be obtained. He follows 

 with a statement of his own that in an eight year old tree 14-2 ounces 

 was obtained, and further states thai the trees might be bled twice a 

 year. This doubling of the yield would make Dr. Weber's return 

 quite comparable with ours, as our 14 ounces was the result of a 

 single bleeding, and it would therefore make our original estimate of 

 2 lbs. per tree practically the same as his own, a point which 

 corroborates our statement as to yield, independent of the evidence 

 afforded by our subsequent unpublished experiment-. 



