'ii Inquiry tuts the Laws of Afflnitj, 



a certain degree, the a^l'ion of an excefs of acid or of bafe (Art. V. No. 4), as well as that 

 of another acid, or a foreign bafe. The only difference between them in this refpe£t de- 

 pends on the force of cohefion, which may a£t more or lefs ftrongly to produce cryftallifa- 

 tion, which is peculiar to certain proportions of the acid and its bafe, probably in confe- 

 quence of the figure aflumed by the particles of which the combination confifts. 



5. When an acid has the property of forming a precipitate, by combining with a bafe, it 

 has been fuppofed to poflcfs a greater affinity for that bafe than the acid with which it was 

 before combined, without even examining to what point the new acid may have effe£l:ed 

 the decompofition ; and without confidering that an oppofite decompofition would have 

 taken place merely by a change of the proportions, and might confequently in that cafe 

 have juftified an oppofite conclufion. 



In this manner as the tartareous acid has the property of forming, with pot-afh, an aci- 

 dulous fait of difficult folubility, and confequently affords a precipitate with all thofe falts 

 that have pot-afh for their bafe, and are not diluted with too great a quantity of water, it 

 has been fuppofed to have a greater affinity for pot-afh than the other acids. Bergman has 

 made an exception with refpedt to the fulphuric acid, becaufe he fuppofed that the tarta- 

 reous acid could only a£t upon that pot-afh which exceeds the combination of the acidulous 

 fulphate of pot-afh ; a fuppofition which I trufl has been refuted In the preceding numbers. 

 He has alfo excepted the nitric and muriatic acids, becaufe he imagines that the tartareous 

 acid a£ts, with refpe£l to the nitrate and muriate of pot-afli, in the fame manner as with 

 the fulphate ; and neverthelefs he has not afcertained the exiftence of an acidulous nitrate 

 and muriate of pot-afh fimilar to the acidulous fulphate of pot-afh. 



He alfo concludes, from experiments made with the falts which have foda for their bafe, 

 without however making known thefe experiments, that the tartareous acid ought to be 

 placed after the oxalic acid; but, thefe exceptions apart, the tartareous acid, according to 

 him, completely decompofes all the other falts that have a fixed alkali for their bafe- 



What embarraiTes Bergman is, that the tartareous acid does not produce a precipitate 

 with the falts which have foda for their bafe. He believes that this apparent difference is a 

 confequence of the foda not having the property of forming a fait of fparing folubility with 

 an excefs of acid ; but then the indication which is thought to afford evidence of the decom- 

 pofition is wanting ; and it becomes neceflary to be fatisfied with the probability, that the 

 affinities of one fixed alkali follow the fame order as thofe of the other. 



All this claflTification of aflSnities is founded upon the falfe fuppofition, that one acid 

 will expel another from its combinations by its aflnnity alone, confidered as a conftant force ; 

 - and this fuppofition neceflTarily demands feveral others, in order to explain as exceptions, 

 thofe fa£ls which are naturally derived from a general property. 



6. I have examined the decompofition of the acidulous tartrite of pot-afli, by the nitric acid, 



which, according to the received opinions, then alfo adopted by me, ought to decompofe 



it, by completely depriving it of its bafe. I therefore put fome acidulous tartrite of pot-afh 



and nitric acid in digeftion together, and obtained by cooling, fome fine cryftals of nitrate 



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