An exhaustive series of experiments have been carried out at 
different times, and under varying conditions, with the apparatus, 
using different fuels in the furnace, e.g., coal, coke, and charcoal, 
or mixtures of these. 
The chief difficulty, which it is hoped may eventually be 
surmounted, is the regulation of the requisite temperature in the 
retorts. A sufficiently high temperature must first be obtained 
fo start the reaction, and secondly this temperature must not be 
greatly exceeded otherwise the carbon bisulphide will be again 
broken down. Till the present time, both in the original 
apparatus and in modified forms of this apparatus, the necessary 
conditions have not been obtained. 
Experiments are still being carried on, and recently an 
earthenware retort has been tried, as the corrosive action of the 
sulphur on the iron retort at the elevated temperature used, was 
found to disintegrate the latter completely in a very short time. 
In the event of this small field retort and furnace being 
unsuccessful, either a large plant will have to be erected for the 
production of this insecticide, on the same principle as those at 
present in vogue, or the liquid will have to be imported for 
agricultural purposes; the latter method has many disadvantages 
and there is no reason why the compound^ should not be success- 
fully manufactured here if necessary precautions are taken. 
Effects of Arsenical and Sulphur Fumes from Tin 
Roasting Furnaces on Vegetation. 
The effects of arsenious acid on the root or stems of a plant 
immersed in a solution of the acid is said to be similar to that of 
hot water, the foliage turns a brown colour and rapidly withers. 
Plants grown in earth containing arsenic are said to only take up 
minute quantities, and the toxic effect is negligible. The principal 
effect of arsenical fumes from factories on vegetation is that of 
defoliation. 
I 
In order to demonstrate definitely the effects of the noxious 
fumes, chiefly arsenious acid and sulphur dioxide, in the fumes 
from the tin roasting furnaces in these* States, a small model 
furnace (about quarter of the original size) has been erected by 
the Director of Agriculture in the grounds of the Institute for 
Medical Research, and a long atap shed, open at both ends and 
standing on long poles, has been added for experimental 
observations. 
In this furnace low grade tin ores containing high 
percentages of mispickel (arsenical iron pyrites) are to be roasted,. 
