of elective Attractions. •SB 



upon general principles, a multitude of scattered pbsEao- 

 niena, and to reject many which have been mentioned as 

 probable, though doubtful, with the omisslpn of a very few 

 only which have keen stated as ascertained. Thjs arrange- 

 ment simply depends on the supposition, that the attractive 

 force, which tends to unite any two substances, may always 

 be represented by a certain constant quantity. 



From this principle it may be inferred, in the first place, 

 that there must be a sequence in the simple elective attrac- 

 tions. For example, there must be an error in the common 

 tables of elective attractions, in which magnesia stands above 

 ammonia under the sulfuric acid, and below it under the 

 phosphoric, and the phosphoric acid stands above the sul- 

 furic under magnesia, and below it under ammonia, since 

 such an arrangement implies, that the order of the attrac- 

 tive forces is this ; phosphate of magnesia, sulfate of mag- 

 nesia, sulfate of ammonia, phosphate of ammonia, and 

 again phosphate of magnesia ; which forms a circle, and 

 not a sequence. We must therefore either place magnesia 

 above ammonia under the phosphoric acid, or the phos- 

 phoric acid below the sulfuric under magnesia; or we 

 must abandon the principle of a numerical representation in 

 this particular case. 



In the second place, there must be an agreement between 

 the simple and double elective attractions. Thus, if the 

 fluoric acid stands above the nitrfc under barita, anfi below 

 it under lime, the fluate of barita cannot decompose the ni- 

 trate of lime, since the previourattractions of these two 

 salts are respectively greater, than the divellent 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 form a precipitate with the nitrate of 

 bar.ta, there has been some fallacy in the experiment. 



The third proposition is somewhat less obvious, but per- 

 haus of greater utility : there must be a continued sequence 

 in 'the order of double elcdive attractions ; that is, between 

 any two acids, we may place the dilferent l)ases in such an 

 order, that any two *>aUs, resulting from ihe.r union, shall 

 J) 4 always 



