214 Mr. Chenevix*s Analysis of 
same specimen. If nitric acid is used not sufficiently strong, 
part of the ore remains untouched, and vrill require subsequent 
treatment, always disadvantageous in delicate operations. If 
the acid is too strong, a great part of the sulphur is converted 
into sulphuric acid ; so that, in either case, there is room for 
error. I thought that, to avoid this, (except in cases where 
any metal which, with sulphuric acid, forms an insoluble salt, 
was present,) strong nitric acid might be used, and all the sul- 
phur converted into acid. If potash, soda, * or ammonia, are 
used as precipitants of the different metals, the quantity of 
sulphur may be easily ascertained. I took a given weight of 
sulphur, and converted it into sulphuric acid, by means of 
nitric acid. I then neutralized and evaporated it. Nitrate of 
barytes, poured in, gave a precipitate which, in one experiment, 
indicated a proportion of sulphur equal to 14,4, and in another 
to 14,6, contained in one hundred of sulphate of barytes. A 
difference so trifling need not be regarded. According to 
M. Lavoisier, sulphuric acid contains 71 of sulphur, and 
29 of oxy gen ; and, according to the synoptic tables of M. 
Fourcroy, sulphate of barytes contains 33 per cent, of sul- 
phuric acid; therefore, by this calculation, one hundred of sul- 
phate of barytes contain 23,43 of sulphur, instead of 14,4, or 
14,6. I do not pretend to account for so great a difference in 
these results but that very difference led me (by exciting me 
to doubt those which I had obtained, and inducing me to fre- 
quent repetition,) to a more positive conviction of the proportions 
• See note in page 197. 
f I was particularly cautious in ascertaining that, during that experiment, no 
sulphureous acid had been produced, the formation of which would have easily 
accounted for any difference. 
