45 
OBSERVATIONS. 
§ 3 - 
V 
(a) Upon half an ounce of tin ore fine¬ 
ly powdered was poured 4 ounces of aqua 
regia, compofed of two parts of marine 
and one part of nitrous acid. The me¬ 
tallic part was moftly diffolved in 24 hours 
without heat, and the fulphur rofe to the 
furface. After the folution was digefted 
again in a fand bath for two hours, it 
was diluted with water and filtred. There 
remained two grains of fandlike earth : 
the feparated fulphur weighed y 5 grains. 
But the fulphur wanting a pure yellow 
colour, appeared Bill to contain fome 
metallic parts: it was flowly deflagrated, 
and left 17 grains @f a black grey refi- 
duum. 
(b) To the filtred metallic folution I 
added fixed vegetable alkali. But ob- 
ferving the firft precipitate, which had a 
whitifli colour approaching to yellow, to 
be 
