VOL. LXXIII.J PHILOSOPHICAL TRANSACTIONS. 333 



100 grs. of real nitrous acid, whose proportion to water should be as 1 to 8 or 9. 

 In this last case, a gentle heat may be applied. This solution affords 44 cubic 

 inches of nitrous air. The calces of bismuth are also soluble in this acid. 



Bismuth in marine acid. — 400 grs. of spirit of salt, whose specific gravity is 

 1.220, dissolved only 3 or 4 grs. of bismuth. 



Nickel in vitriolic acid. — 100 grs. of concentrated vitriolic acid dissolve about 

 4 of nickel, with the assistance of a strong heat. The calces of nickel are 

 much more soluble. 



Nickel in nitrous acid. — 100 grs. of nickel require for their solution 1 12 grs. 

 of nitrous acid, whose proportion to water is as 1 to 1 1 or 12, assisted with a 

 moderate heat. A concentrated acid acts so rapidly that much is dissipated. 

 The product of nitrous air is 79 cubic inches. The calces of nickel are also so- 

 luble in this acid. 



Nickel in marine acid. — 200 grs. of spirit of salt, whose specific gravity is 

 1 .220, dissolved 4 or 5 grs. of nickel, without the assistance of heat. A weaker 

 acid dissolves less, and requires the assistance of heat. In all these cases of diffi- 

 cult solution more of the metal will be taken up by distillation and cohobation; 

 but the proportion will be difficult to assign. The calces of nickel are also diffi- 

 cultly soluble in this acid. 



Col-alt in vitriolic acid. — 100 grs. of cobalt require 450 grs. of real acid, 

 whose proportion to its water is not less than 1 to -^, and a heat of 270° at 

 least. By pouring warm water on the dephlogisticated mass a solution is ob- 

 tained. The calces of cobalt are still more soluble; even a dilute acid will serve. 



Cobalt in nitrous acid. — 100 grs. of cobalt require 220 grs. of real nitrous 

 acid, whose proportion to water is as 1 to 4, giving towards the end a heat of 

 180°. The calces of cobalt are soluble in this acid. 



Cobalt in marine acid. — 100 grs. of spirit of salt, whose specific gravity is 

 1.178, dissolve, with the assistance of heat, 1\ grs. of cobalt. A more con- 

 centrated acid will dissolve more. The calces of cobalt are more soluble in this 

 acid. 



Regulus of antimony in vitriolic acid. — 100 grs. of regulus of antimony re- 

 quire for their solution 725 grs. of real acid, whose proportion to water is as 1 

 to T V, and a heat of 400°. More regulus should be employed than is expected 

 to be dissolved, and the resulting salt requires a large quantity of water to dis- 

 solve it; for the concentrated acid lets fall much when water is added to it. A 

 less concentrated acid will also dissolve this semi metal, but in smaller quantity. 

 The calces of antimony, even diaphoretic antimony, are something more soluble. 



Regulus of antimony in nitrous acid. — 100 grs. of this semi-metal require 900 

 grs. of real nitrous acid, whose proportion to water is as 1 to 1 2, aided with a 



