348 Researches respecting 



potash, and not diluted with too large a quantity of water, 

 it has been concluded that it has more affinity for potash than 

 the other acids. Bergman has excepted the sulphuric acid, 

 because he supposed that the tartareous acid could act only 

 on the potash redundant to the combination of the acidulous 

 sulphat of potash ; a supposition which I think I have al-» 

 ready destroyed in the preceding articles. He has excepted 

 also the nitric and muriatic acids, because he supposed that 

 the tartareous acid showed the same phaenomena in regard to 

 ^he nitrat and muriat of potash as in regard to the sulphat ; 

 though he has not ascertained the existence of an acidulous 

 nitrat and muriat of potash analogous to the acidulous sulphat 

 of potash. 



He also concludes, from experiments made on salts having 

 a base of soda, but without making the experiments known, 

 that the tartareous acid ought to be placed after the oxalic 

 acid : but, not to dwell on these exceptions, the tartareous 

 acid, according to him, decomposes completely all the other 

 salts with a base of fixed alkali. 



What embarrasses Bergman is, that the tartareous acid 

 produces no precipitate with salts that have a base of soda. 

 In his opinion, this apparent difference depends on the soda 

 not having the property of forming a salt but little soluble, 

 by taking up an excess of acid ; but in that case there is no 

 evidence of a decomposition, and we are to be satisfied with 

 the probability that the affinities of the one fixed alkali follow 

 the same order as those of the other. 



All this classification of affinities is founded on the false 

 supposition, that one acid expels another from its combina- 

 tions by its affinity alone considered as a constant force; and 

 this supposition renders others necessary in order to explain, 

 as exceptions, those facts necessarily arising from a general 

 property. 



6th, I have examined the decomposition of acidulous tar- 

 trite of potash by the nitric acid, which, according to the 

 received ideas, which I then adopted, ought to decompose it. 

 Uy seizing entirely on its base. I digested acidulous taltrite 

 of potash and nitric acid, and obtained, by cooling, beautiful 

 crystals of nitrat of potash. I repeated the operation several 



timfes. 



