KUMEKICAL TABLE OF ELECTIVE ATTBACTiOSS. 357 



In the second place, there mast be an agreement between The simple and 

 the simple and double elective attractions. Thus,i£ the fluoric tionsiaust 

 acid stands above the nitric under barita, and below it under agree, 

 lime, theiluateof barita cannot decompose the nitrate of lime, 

 since the previous attractions of these two salts are respec- 

 tively greater, than the div client attractions of the nitrate of 

 barita and the fluate of lime. Probably, therefore, we ought 

 to place the fluoric acid below the nitric under barita; and 

 we may suppose, that, when the fluoric acid has appeared to 

 forma precipitate with the nitrate of barita, there has been 

 some fallacy in the experiment. 



The third proposition is somewhat less obvious, but per- A continued 

 haps of greater utility :' there must be a continued sequence ^ T » double 

 in the order of double elective attractions ; that is, between attractions, 

 any two acids, we may place the different bases in such an 

 order, that any two salts, resulting from their union, shall 

 always decompose each other, unless each acid be united to 

 the base nearest to it : for example, sulfuric acid, barita, po- 

 tass, soda, ammonia, strontia, magnesia, glycina, alumina, 

 zirconia, lime, phosphoric acid. The sulfate of potass de- 

 composes the phosphate of barita, because the difference of 

 the attractions of barita for the sulfuric and phosphoric 

 acids is greater than the difference of the similar attractions 

 of potass ; and in the same manner the difference of the at- v 

 tractions of potass is greater than that of the attractions of 

 soda ; consequently the difference of the attractions of ba- 

 rita must be much greater than that of the attractions of 

 soda, and the sulfate of soda must decompose the.phosphate 

 of barita: and in the same manner it may be shown, that 

 each base must preserve its relations of priority or posteri- 

 ority to every other in the series. It is also obvious, that, 

 for similar reasons, the acids may be arranged in a conti- 

 nued sequence between the different bases; and when all 

 the decompositions of a certain number of salts have been 

 investigated, we may form two corresponding tables, one 

 of the sequences of the bases with the acids, and another 

 of those of the acids with the different bases ; and if either Correction of 

 or both of the tables are imperfect, their deficiencies may ^ ursm k u " 

 often be supplied, and their errours corrected, by a re- 

 peated comparison with each other. 



In 



