IGO 
Analyses of the Ashes of Plants. 
by nitric acid would give the true quantity of sulphur. The fol- 
lowing experiment is unfavourable to this idea: — 
One thousand grains of white mustard-seed were digested in 
strong nitric acid, the action being carried only so far as to break 
down the seed into a uniform pulpy mass; the acid liquid was 
diluted with water and the whole allowed to digest for 24 hours ; 
it was then filtered and precipitated by nitrate of barytes. 
It gave . . . 27*880 of sulphuric acid. 
This is less than the true quantity of sulphuric acid ; and although 
it is impossible to say at what particular point the whole sulphur 
of the plant is converted into sulphuric acid, we should not con- 
ceive it safe to stop so far short of perfect oxidation of the vege- 
table substance. At the same time, as the following experiment 
shows, it is quite possible to obtain the whole sulphur of the 
plant without carrying on the operation to perfect oxidation. 
One thousand grains of white mustard-seed were treated with 
strong nitric acid, and fresh additions of acid made until the 
action, though not by a good deal complete, had yet lost much of 
its violence ; the acid liquid was diluted and filtered, and precipi- 
tated by nitrate of barytes^ as usual. 
It gave . . . 29 '672 of sulphuric acid. 
It is fair to state that this method of oxidating sulphur, which 
is common enough in chemical operations, has been before ap- 
plied to the estimation of the sulphur of plants. A series of 
estimations of the sulphur and phosphorus of plants, extending 
over a large number of specimens, and conducted apparently with 
great care, is published in the ' Memoirs of the Chemical Society ' 
(part XX.), by Mr. Clifton Sorby. The results there given differ 
from our own considerably in some instances, although but little 
weight is due to this circumstance, seeing that no two specimens 
have been found by us precisely alike. From the account of the 
process given in the Memoirs we are inclined to think that Mr. 
Sorby may not in all cases have obtained the whole sulphur of 
the plant for want of a more perfect oxidation than he seems to 
have attained. And indeed, however satisfactory this method 
may be in the case of seeds, it is radically defective for the esti- 
mation of sulphur in some other vegetable substances, such as 
straw, leaves, &c". 
We had commenced a series of examinations of the straws of 
beans and peas by this plan, but were compelled to abandon the 
experiments on account of the great want of uniformity in the 
results. In some cases scarcely a trace of sulphate of barytes 
was obtained, when the acid liquid, after treatment with nitrate 
of barytes, had been allowed to stand for many days — in other 
