ON ARSENIC 135 



some arsenic was sublimed. After it was grown cool, it 

 proved to be a yellow mass, upon which a number of grey 

 elevated streaks appeared ; they were like a vegetation, and 

 were formed during the distillation. This yellow mass was 

 boiled in water, when the acid dissolved, and a yellow powder 

 remained behind, which, when treated with charcoal powder, 

 yielded a regulus of arsenic, but was not reduced itself, (c) 

 The solutions of nickel in acids are not precipitated by the 

 acid of arsenic, neither is there any precipitation from its 

 solution in vinegar ; but the neutral arsenical salts precipitate 

 a whitish green powder. 



SECTION XXXV. UPON MANGANESE. 



(a) The acid of arsenic dissolves a little manganese 

 during digestion ; fixed alkalies precipitate a white powder 

 from it. (b) When distilled with acid of arsenic, a little 

 arsenic was sublimed. The mass entered into a kind of 

 fusion, but the acid contained no more of the manganese 

 than it did before, (c) Phlogisticated manganese dissolves 

 readily in acid of arsenic ; but whenever the acid arrives at 

 the point of saturation, the solution coagulates to little 

 crystals, (d) The solutions of manganese in the mineral 

 acids are not precipitated by the acid of arsenic, though 

 they readily are by the neutral arsenical salts. Manganese 

 dissolved in vinegar is precipitated by the acid of arsenic. 

 (c) These precipitates, which consist of phlogisticated man- 

 ganese and of acid of arsenic, were distilled in such a heat 

 that the retort at last melted, but no arsenic was sublimed, 

 nor would they enter into fusion, but retained their white 

 colour ; however, when mixed with charcoal powder in a 

 crucible, they flowed, and regulus of arsenic arose in the 

 form of vapour, while the manganese remained behind. 



