VOL. LXXVI.] PHILOSOPHICAL TRANSACTIONS. 75 



whitened; but by agitation it may be made to take up about its bulk, and then 

 becomes very turbid. One measure of caustic vegetable alkali, whose specific 

 gravity was 1.C43, absorbed nearly 4 measures of alkaline hepatic air. It was at 

 first rendered brown by it; but after some time it got clear, sulphur was 

 deposited, and the surface of the mercury blackened. This shows that alkalis 

 are not dephlogisticated by silver or other metals, as Mr. Baume imagined, but 

 only cleared of part of the sulphur, which they commonly contain, it being 

 formed by the tartar vitriolate contained in the plant, and coal, during com- 

 bustion. One measure of caustic volatile alkali, whose specific gravity was 

 0.9387, absorbed 18 of hepatic air. If the caustic liquor contained more 

 alkali, it would absorb more hepatic air, as 6 measures of hepatic unite to 7 of 

 alkaline air; and thus the strength of alkaline liquors, and their real contents, may 

 be determined better than by any other method. Also the smoking liquor of 

 Boyle, which is difficultly prepared in the usual way, may easily be formed by 

 placing the volatile alkali in the middle glass of Dr. Nooth's apparatus for making 

 artificial mineral waters, and decomposing artificial pyrites-, or liver of sulphur, 

 in the lower glass, by marine acid. Oil of olives absorbs nearly its own bulk of 

 this air, and obtains a greenish tinge from it. But new milk scarcely absorbs -^ 

 of its bulk of this air, which is very remarkable, and is not in the least coagu- 

 lated. Oil of turpentine also absorbs its own bulk of this air, and even more; 

 but then becomes turbid. Water seems also to precipitate this air from it, for 

 when shaken with it a white cloud appears. Spirit of wine, whose specific gra 

 vity was 0.835, absorbed nearly 3 times its bulk of this air, and became brown. 

 By this means sulphur may be combined with spirit of wine much more easily 

 than by Count Lauragais's method, the only hitherto known. Water precipi- 

 tates the sulphur in part. 



Of the Properties of Water saturated with Hepatic air. — This water turns 

 tincture of litmus red. It does not affect lime-water. It does not form a cloud 

 in the solution of marine, though it does in that of acetous baro-selenite. The 

 solutions of other earths in the mineral acids are not altered in it. When 

 dropped into a solution of vitriol of iron or marine salt of iron, it produces a 

 white precipitate. In nitrous salt of copper it causes a brown precipitate, and 

 the liquor is changed from blue to green: The precipitate re-dissolves by agita- 

 tion : in vitriolic of copper it forms a black precipitate. The solution of tin in 

 aqua regia is precipitated by it of a yellowish white colour; that of gold, black; 

 that of regulus of antimony, red and yellow ; that of platina, red mixed with white. 



The solution of silver in the nitrous acid, and also that of lead, whether in 

 acetous or nitrous acid, are precipitated black. If the solutions are not perfectly 

 saturated with metal, the precipitates will be brown or reddish brown, and may 

 be re-dissolved by agitation. The nitrous, solution of mercury is precipitated of 



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