'872 Dr. Watson’s Experiments and. 
mony by folutions in acids, I thought it not improbable, 
that it might be feparated from lead ore by the fame 
means, and the fuccefs of the following experiment 
abundantly juftified the conjecture. 
Upon ten ounces of lead ore, cieanfed as in the pre- 
ceding experiment, I poured five ounces of the ftrongeft 
fuming fpirit of nitre; this ftrong acid not feeming to 
a 
a<5t upon the ore, I diluted it with five ounces of water ; 
a violent ebullition, accompanied with red fumes, imme- 
diately took place ; the folution of the ore in this men- 
ftruum became manifeft, and when it was finifhed, there 
remained floating upon the furface of the menftruum a 
cake of fine yellow fulphur, perfectly refembling com- 
mon fulphur. 
I repeated this experiment a great many times, in or- 
der to afcertain the quantity of fulphur contained in lead 
ore, and feparable therefrom by folution in acid of nitre. 
The refults of different experiments were feldom the 
fame: the matter feparable from the ore by folution, 
after being repeatedly walhed in large quantities of hot 
water, in order to free it from every faline admixture, 
fometimes amounted to more, fometimes to lefs than 
one-third the weight of the ore. This matter may, for 
the fake of diftinftion, be called crude fulphur. Its ap- 
parent purity might induce a belief that it contained no 
hetero- 
