358 NUMERICAL TABLE OF ELECTIVE ATTRACTIONS. 



Tables formed In forming fables of this kind from the cases collected by 

 lected by Four- Fourcroy, I have been obliged to reject some facts, which 

 troy. were evidently contradictory to others, and these I have not 



thought it necessary to mention ; a few, which are positively 

 related, and which are only inconsistent with the principle of 

 numerical representation, I have mentioned in notes but many 

 others, which have been stated as merely probable, I have 

 omitted without any notice. In the table of simple elective 

 attractions, I have retained the usual order of the different 

 substances; inserting again in parentheses such of them as 

 require to be transposed, in order to avoid inconsequences 

 in the simple attractions : I have attached to each combina- 

 tion marked with an asterisk the number deduced from the 

 double decomposition, as expressive of its attractive force ; 

 and where the number is inconsistent with the corrected or- 

 der of the simple elective attractions, I have also enclosed 

 it in a parenthesis. Such an apparent inconsistency may 

 perhaps in some cases be unavoidable, as it is possible, that 

 the different proportions of the masses, concerned in the 

 operations of pimple and compound decomposition, may 

 sometimes cause a real difference in the comparative magni- 

 tude of the attractive forces. Those numbers, to which no 

 asterisk is affixed, are merely inserted by interpolation, and 

 they can only be so far employed for determining the mutual 

 actions of the salts to which they belong, as the results 

 which they indicate would follow from the comparison of 

 any other numbers, intermediate to the nearest of those, 

 which are more correctly determined. I have not been able 

 to obtain a sufficient number of facts relating to the metal- 

 lic salts, to enable me to comprehend many of them in the 

 tables. 

 Divisions of at- It has been usual to distinguish the attractions, which pro- 

 duce the double decompositions of salts, into necessary and 

 superfluous attractions ; but the distinction is neither very ac- 

 curate, nor very important : they might be still farther divided 

 accordingly as two, three, or the whole of the four ingre- 

 dients concerned arc capable of simply .decomposing the salt 

 in which theyare not contained; and if two, accordingly as 

 they are previously united or separate: such divisions would 

 however merely tend to divert the attention from the natural 

 operation of the joint forces csneerned. 



5 It 



