VOL. LXXII.] PHILOSOPHICAL TRANSACTIONS. • I7S 



into a yellow powder. Half an oz. of the acid was sufficient to corrode 2 scr. 

 of tin, with the assistance of heat. It emitted a very disagreeable smell, like 

 that which is produced by the action of the muriatic acid upon zinc. The small 

 quantity of turbid supernatant liquor could not be rendered clear by filtration 

 through many folds of blotting paper. But after standing at rest for a short 

 time, a yellowish powder was deposited, while the supernatant liquor, now be- 

 come clear, appeared of a beautiful rose-colour. — This corroded calx of tin being 

 digested in distilled water, and the water being afterwards filtrated and evaporated, 

 a white deliquescent salt was obtained; and on adding to this salt a fresh quantity 

 of the acid, the rose-colour was again produced, without any diminution of the 

 quantity of sediment. 



Exp. 89. Bismuth, in its metallic state, was not dissolved by this acid ; but 

 its calx was. When the solution was diluted with water, it became milky and de- 

 posited a white sediment ; but it underwent no change on adding either the 

 vitriolic or muriatic acid. 



Exp. go. Regulus of cobalt was not dissolved by it ; but its calx was. From 

 the solution distilled with nitre a salt was obtained, which being dissolved in 

 water gave a sympathetic ink. 



* Exp. 91. It had very little action upon regulus of nickel ; but it dissolved the 

 calx of this metal, even without the assistance of heat. The solution was of a 

 greenish colour, and suffered no precipitation on adding the vitriolic and nitrous 

 acids. 



Exp. 92. White arsenic was dissolved with difficulty, even when assisted by heat. 



Exp. 93. The Ilfeld ore of manganese was dissolved by this acid. It first 

 separated a black powder from the ore, and afterwards dissolved the ore itself, 

 in considerable quantity. The acid, which acquired a brown colour by digestion 

 with other metals, suffered no change by digestion with the manganese. The 

 solution, which emitted a smell like that which is given out from a solution of 

 tin, had a metallic taste, and was rendered somewhat turbid by the addition of 

 water. When Beguin's tincture was added to the solution, it acquired a red 

 colour, and the precipitate which it threw down very abundantly, being dried, 

 was of the same colour. 



Precipitations of metals, dissolved in other acids, produced by commixtion with 

 the acid of fat. — Exp. 94. Gold. Having obtained some beautiful yellow crys- 

 tals (not unlike in figure to the crystals of common salt) from a solution of gold 

 in aqua regis, which solution had been exposed to the open air, Dr. C. dissolved 

 them in distilled water and added the acid of fat to the solution, whereupon a 

 yellow precipitate was thrown down. This precipitate being edulcorated and 

 dried, it afterwards attracted moisture from the air. 



Exp. 95. Plalina. This acid being added to a solution of platina in aqua 



