250 Dr. Young’s Account of a numerical Table 
have served as the bases of the determination, independently 
of any hypothesis, and without being liable to the contingent 
necessity of any future alteration, in order to make room for 
the introduction of the affections of other substances ; and this 
method enables us also to compare, upon general principles, 
a multitude of scattered phenomena, and to reject many which 
have been mentioned as probable, though doubtful, with the 
omission of a very few only which have been stated as ascer- 
tained. This arrangement simply depends on the supposition, 
that the attractive force, which tends to unite any two sub- 
stances, 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 sulfuric 
under magnesia, and below it under ammonia, since such an 
arrangement implies, that the order of the attractive forces is 
this ; phosphate of magnesia, sulfate of magnesia, 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 phosphoric acid below the sulfuric 
under magnesia ; or we must abandon the principle of a nu- 
merical 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 nitric under barita, and below it under 
