NOTES. 
253 
NOTES. 
MM. Michelin & Cie.’s i^naiyses of Ceylon India- 
rubbers prepared by Mr. Parkin. 
The various methods used for the preparation of indiarubber from 
the latex of Hevea brasiliensis, Castilloa elastica, and Manihot 
Glaziovii, the Para, Panama, and Ceara rubbers respectively, have been 
described in the “ Circular ” of this Department (Vol. I., Nos. 4, 11, and 
12-14). Samples prepared by these various methods were sent to 
MM. Michelin et Cie. of Clermont Ferrand, the well-known rubber 
manufacturers, who generously undertook their analysis, the results of 
which are given below. 
It may be well first to briefly describe the methods of preparation of 
each sample. Prior to Mr. Parkin’s work, the method used was that 
described in Circular 4, p. 29 ; V-shaped incisions were made in the 
tree-trunk in vertical rows, and a gutter of clay formed round the base 
of the tree, leading the milk into cocoanut shells, in which it was 
simply allowed to dry. Samples of Para rubber thus prepared are 
described below as shell rubber. A considerable quantity of milk dries 
on the tree in working this process, and the long strings thus formed 
are rolled up into small balls, described below as ball rubber ; these 
contain a large admixture of pieces of bark and other impurities, and 
have a lower market value than the shell rubber, but, on the other hand, 
they are better dried and so less liable to putrefaction. The shell 
rubber being in large pieces did not dry rapidly, and became more or 
less putrid in drying, thus spoiling its quality to some extent. It was 
valued in London on two or three occasions at a little lower price than 
the best Para rubber from the Amazon Valley. The latter, as is well 
known, appears on the market in the form of large slabs, formed by 
holding the milk on a wooden paddle in the smoke of burning palm 
nuts. It is thus coagulated and dried layer by layer, and a product of 
remarkably uniform quality and free from putrefaction is obtained. 
Analysis of the smoke showed that the result was due to the coagu- 
lation of the milk by the acetic acid contained in it, and its preservation 
from putrefaction by the creosote also present. Mr. Parkin used these 
facts as the basis of his process, coagulating the milk by acetic acid in 
the quantity necessary to give the best result, and adding a small 
amount of creosote to prevent putrefaction. In this way the process 
was brought under control, and the blackening of the rubber due to 
the carbon in the smoke was avoided. The method now used for Para 
rubber is to place a tin vessel containing water under each V cut in the 
( 31 ) 
