Metallic Oxydes and. Earths. (219 
vo 
16, Marine’ acid precipitated the litharge. 
‘Upon being left to ftand, the lin-feed and train oils 
_affumed a much darker hue, than they had) previ- 
ous to the addition of the acid. 
17. © Alcalies coagulated the oils, as in the former 
“experiments with them. ‘ 
18... 'Two ounces of. Sperma Ceti cil and half 
a drachm of red lead were digefted during eight 
hours. ‘The oil feemed not in the leaft changed ; 
“but a fmall quantity of the lead remained fufpend- 
-ed; and gave it a flight pink caft. The heat, the 
“nextday, was gradually increafed with as little fuc- 
-cefs, till the oil being brought to nearly a boiling 
heat, it became dark and difcoloured. 
1g. Lin-feed oil was tried in the fame proportions, 
-with the like refult. 
20. ‘Train oil was treated, in the fame mode 
-as the others, with one drachm of red Jead. On in- 
creafing the heat, it formed a very thick, dark 
coloured mafs. 
21. White lead, and the oxyde of copper, which 
is formed upon the diftillation of acetated copper, 
had-tne fame effe& with the red lead. But lefs of 
the oxyde of copper appeared to be diffolved, than © 
of thofe of lead. 
Not meeting with the fuccefs, from the digeftion 
of the oils with the metallic oxydes, which I was at 
firtt led to expect, I fubmitted them to the action 
of different pure aérated earths under the fame 
degrees of heat. ‘ 
| 22. ‘Two 
