32 1 
of the magnetical Pyrites , &c. 
place ; and a pale yellowish-green solution was formed. The 
residuum was then again digested with two parts of muriatic 
acid mixed with one of nitric acid; and a quantity of pure 
sulphur was obtained, which, being dried, weighed 14 grains. 
B. The acid in which the residuum had been digested, 
was added to the first muriatic solution ; some nitric acid was 
also poured in, to promote the oxidizement of the iron, and 
thereby to facilitate the precipitation of it by ammonia, which 
was added after the liquor had been boiled for a considerable 
time. The precipitate thus obtained was boiled with lixivium 
of potash; it was then edulcorated, dried, made red-hot with 
wax in a covered porcelain crucible, was completely taken up 
by a magnet, and, being weighed, amounted to 80 grains. 
C. The lixivium of potash was examined by muriate of 
ammonia, but no alumina was obtained. 
D. To the filtrated liquor from which the iron had been pre- 
cipitated by ammonia, muriate of barytes was added, until it 
ceased to produce any precipitate; this was then digested with 
some very dilute muriatic acid, was collected, washed, and, after 
exposure to a low red heat for a few minutes in a crucible of 
platina, weighed 155 grains. If therefore the quantity of sulphur, 
converted into sulphuric acid by the preceding operations, and 
precipitated by barytes, be calculated according to the accurate 
experiments of Mr. Chenevix, these 155 grains of sulphate of 
barvtes will denote, nearly, 22.50 of sulphur; so that, with the 
addition of the 14 grains previously obtained in substance, the 
total quantity will amount to 36.5 o. 
E. Moreover, from what has been stated it appears, that the 
iron which was obtained in the form of black oxide, weighed 80 
grains ; and, by adding these 80 grains to the 36.50 of sulphur, 
Tt 2 
