On Svper-acid and Snl-acid Salfs. 279 



the alkali of three equal quantities of the same salt to satu- 

 rate the three remaining parts of acid. 



The limit to the decomposition of super-oxalate of potash 

 by the above acids, is analogous to that which occurs whca 

 sulphate of potash is decomposed by nitric acid; for ii\ this 

 case also, no quantity of that acid can take more than half 

 the potash, and the remaining salt is converted into a definite 

 super-sulphate, similar to that obtained by heat in the third 

 experiment. 



It is not improbable that many other changes in chemistry., 

 supposed to be influenced by a general redundance of some 

 one ingredient, may in fact be limited by a new order of 

 affinities taking place at some dctinite proportion to be 

 expressed by a simple multiple. And though the strong 

 power af crvstallizins; in oxalic acid, renders the modifica- 

 tions of which its combinations are sysccptible more distinct 

 than those of other acids, it seems probable that a similar 

 play of affinities will arise in solution, when other acids ex- 

 ceed their base in the .same proportion. 



In order to determine whether oxalic acid is capable of 

 unitincT to potash in a proportion intermediate between the 

 double and quadruple quantity of acid, I neutralized forty- 

 eight grains of carbonate of potash with thirty grains of oxalic 

 acid, and added sixty grains more of acid, so that I had two 

 parts of potash of twentv-four grains each, and six equivU' 

 lent quantities of oxalic acid of fifteen grains each, in so- 

 lution, ready to crystallize together, if disj)osed to unite, 

 in the proportion of three to one ; but the first portion of 

 salt that crystallized, was the common binoxalate, or salt 

 of sorrel, and a portion- selected from the after crystals 

 (which differed vercy discernibly in their form) was found 

 to contain the quadruple proportion of acid. Hence it is to 

 be presumed, that if these salts could have been perfectly 

 separated, it would have been found, that the two quanti- 

 ties of potash were equally divided, and combined in one 

 instance with two, and in the other with the remaining four 

 out of the six equkalent tjuantitics of acid taken. 



To account for lhi« want of disposition to unite in the pro- 

 '^ 4 portioa 



