5i 
4- The effect on vegetation of a number of isolated roastings of 
arsenical ore will depend on the concentration of the fumes, and the 
period between the roastings, but even if the vegetation is not com- 
pletedly killed, growth will naturally be retarded. 
In confirmation of these results it might be of interest to quote 
the following extract from “Nature,” February 20th, 1908, page 376 : 
“ It has been found that not only are the trees and grass in the 
vicinity of the works injured by the sulphur dioxide and sulphuric 
acid of the smoke (Note : from a copper smelting works in America 
which is stated to produce \\Vz percent, of the world’s supply of 
copper), but the gass is rendered poisonous by arsenic (Note by B. J. 
E. — Cattle would feed on such grass as the arsenic would be taste- 
less ; grass sprayed with Sodium Arsenite in the F. M. S. some time 
ago was the cause of poisoning of a number of cows on an estate.) 
Large settling chambers were found to be much less effective 
than long flues for the arsenic — the loss of animals became much 
greater with the former. 
In the above works, arsenic escaped in considerable quantities 
from flues 300 feet high and caused considerable damage to forests 
and crops. Sulphuric acid was also found in the flues and near the 
furnace. 
The article continues : — “ To this sulphuric acid, together with 
the arsenic with which it is associated, is probably due much of the 
spotting of the leaveslwhich is so common in the vicinity of the works. 
N. B. — The action of the flue dust is of far less importance than 
that of the sulphur dioxide in affecting the growth of plants but the 
arsenic may affect to a greater degree the value of the grass, since it 
renders it poisonous.” 
B. J. Eaton, 
Government Chemist , F.M.S. 
ANALYTICAL NOTES. 
OF RUBBER PLANTS IN THE BOTANICAL GARDENS, 
SINGAPORE. 
Hevea brasiliensis, 
The latex was obtained from one 32 year old tree, tapped 
at 6-30 a.m. No water was added to the latex, and the formalin 
added was carefully measured, so that the amount of pure latex 
is known. In the figures given below this formalin has been correct- 
ed for so that they refer to pure latex. 
