6 
Mr. Spence said that he could confirm the remarks con- 
cerning the existence of arsenic in coals, as he had burnt coal 
pyrites for many years, and had always found a very decided 
amount of arsenic in the sulphuric acid made from it. 
Mr. Ransome called attention to the peculiar symptoms 
described by Berzelius, as produced by selenium ; and he con- 
sidered that some similar symptoms were produced in a 
manner which might be explained if selenium were found in 
coals. 
A Paper was read by William Roberts, M.D., entitled, 
“ On the Estimation of Sugar in Diabetic Urine by the Loss 
of Density after Fermentation.” When a diabetic urine is 
fermented with yeast, its specific gravity previously ranging 
from 1030 to 1050 falls to 1009 or 1002, or even below 1000. 
This result is mostly due to the destruction of the sugar it 
contained, but partly also to the generation of alcohol and its 
presence in the fermented product. 
As the diminution of density must be proportional to the 
quantity of sugar broken up by the ferment, the amount of 
loss evidently supplies a means of calculating how much 
sugar any urine contains — always provided that the remaining 
ingredients of the urine continue unchanged, or become 
changed in some uniform ratio. 
To ascertain the relation between the density lost on fer- 
mentation, and the sugar destroyed, experiments were made 
on the urine of diabetic patients on the following plan : — 
1. The amount of sugar per 100 parts was ascertained by 
the volumetrical method, with Fehling’s test solution. 
2. The density of the urine was taken. 
3. Three or four ounces were then placed in a 12oz. phial, 
with a drachm or two of German yeast, and having lightly 
covered the bottle it was set aside to ferment. 
4. In about twenty-four hours the fermentation was finished 
