ON PRUSSIAN BLUE 283 



> SECTION XIII. 



The precipitating liquor (Sec. xi. (#)), acting upon the 

 netallic solutions by means of a double elective attraction, 

 must present phenomena with these solutions different from 

 those which the pure colouring matter produces, (a) If a 

 quantity of this liquor be poured into a well - saturated 

 solution of gold, the gold precipitates in the form of a white 

 powder ; but if it be added in excess, the precipitate will be 

 redissolved. This solution is colourless, like water. The 

 precipitate is not soluble in acids. (&) The solution of 

 platinum is not changed, (c) Silver is precipitated of a 

 white colour, and of a consistence like that of cheese. If 

 more of the liquor be added, the precipitate is redissolved. 

 This solution is not decomposed either by sal ammoniac or by 

 muriatic acid. The white precipitate is insoluble in acids. 

 (cl) Corrosive sublimate seems to undergo no change on 

 pouring this liquor into a solution of it, though it is really 

 decomposed, being, of all the metallic calxes, the only one 

 which can be dissolved by the colouring matter (Sec. xn. (&)). 

 (e) Mercury dissolved in nitrous acid, without the application 

 of heat, is precipitated in the form of a black powder, which 

 is reduced mercury. (/) Tin dissolved in aqua regia is 

 precipitated of a white colour ; but as the mixture gave out 

 a smell very much resembling the smell of the colouring 

 matter, I examined the precipitate, and found that it was 

 nothing but the pure calx of tin soluble in acids, (g) The 

 solution of bismuth showed the same phenomena, (h) The 

 liquor also produced the same effects upon the solution of 

 butter of antimony ; (i) as likewise upon the solution of well- 

 dephlogisticated calx of iron, (k) Vitriolated copper, dis- 

 solved in water, was precipitated of a yellow citron colour. 



