ike Laws of Jffinity. 349 



times, adding nitric acid until no more nitrat of potash was 

 separated. I then exposed the liquor to a heat sufficient to 

 cause the nitric acid which might be free, to evaporate with- 

 out altering the tartareous acid. After this the liquor had 

 an oily consistence ; it was destitute of smell, and announced 

 neither the existence of nitric acid nor that of potash ; but 

 when exposed to a strong heat there was disengaged a great 

 deal of nitrous gas, the tartareous acid was reduced to char- 

 coal, and its ashes gave a considerable quantity of carbonat 

 of potash. 



7th, In this operation there is separated a part of the nitrat 

 of potash, effected by the crystallizing force of that salt, and 

 carried by it just to the degree when that force is exceeded 

 by the superabundant acid. The acidulous tartar is rendered 

 soluble by the action of the nitric acid, which takes from it 

 at the same time, by crystallization, a part of the base neces- 

 sary for its insolubility. 



On the other hand, tartareous acid added to a solution of 

 nitrat of potash, takes up, to a certain term, the potash from 

 the nitric acid, and forms an acidulous tartrite, which is pre- 

 cipitated ; but, as it has not the property of forming an aci- 

 dulous tartrite of soda little soluble, it does not produce a 

 precipitate with salts having a base of soda. 



In both these cases, every thing that cannot be separated 

 by the. force of cohesion forms a liquid, in which the sub- 

 stances exercise an action proportioned to their present masses. 



Nothing, then, can be concluded in regard to the respec- 

 tive affinity from these separations, which are effected by pre- 

 cipitation or crytallization ; since, by the change of the pro- 

 portions alone, opposite decompositions may be often obtained, 



8th, The precipitation observed to take place, when, in 

 comparing the affinities of two bases, one of them was 

 found to have formed an insoluble combination, gave rise to 

 an error of the same kind ; and it is on this foundation alone 

 that it has been asserted that lime has more affinity than 

 alkali for the fluoric, phosphoric, and arsenic acids : in a 

 Word, for all those which form with it an insoluble combina- 

 tion 5 and, consequently, that it has the property of decom- 

 posing entirely the salts formed by an alkali and these acids. 



This 



