J. W. Langley—Chemical Affinity. 363 
and each particle of aqua regia a force in virtue of which they 
seek each other out, unite and retain each other.”* We al 
ctio 
acid upon iron to a marriage, and says that the combination 
comes rather from love than hate. 
Two of Boerhaave’s successors, St. F. Geoffroy and Torbern 
Bergmann, appear to be the authors of a new conception which 
was subsequently known under the name of Elective Affinity. 
Geoffroy attempts to indicate the order of chemical actions, or 
as we should now eall it, the relative intensity of combining 
power, by arranging several bases in the order in which they 
displace each other. Thus one of his tables was the following: 
Vitriolic Acid.® 
Sel Alkali, fixed. Earths. Copper. 
Sel Alkali, volatile. Tron. Silver. 
It was soon discovered, however, that an order of bases which 
might be correct for one acid would be incorrect for another, and 
that a given substance would take different positions in the two. 
The following, which is a portion of one of Bergmann’s lists 
published in 1788, will show the fact :° 
Gaseous Acid. ( Carbonic.) Acid of Sugar. (Ozalic.) 
Pure heavy earth. ime. 
Pure lime. | Heavy earth. A 
Fixed vegetable alkali. Magnesia. 
Fixed mineral alkali. Fixed vegetable alkali. 
Magnesia, ete. Fixed mineral alkali, etc. 
Interest with all acids, loves them and is also loved by 
them ; accordingly when warmed the acid of the salt (muriatic) 
attaches itself to it, combines with it so that the sal volatile is 
Set free and is distilled to a subtle spirit.” 
The next advance in the direction of precision was made by 
Wenzel,* who, in a work entitled Lehre von den Verwandschafien, 
