i 
‘ 
J. W. Langley—Chemical Affinity. 369° 
3.—The union of heterogeneous atoms is the result of electrical 
attractions.” 
This includes Davy, Ampére, Berzelius and perhaps Patsday. 
4.—“Chemical action results from a constant motion among t 
ultimate particles of bodies, this same movement likewise athe 
risé to the viens of heat, light, and electricity.” 
This is Williamson’s theory of icogeent sions interchange 
between all.mdlecules in solution. e hypothesis has 
also been sustained by Kekulé and Miaslia, 
e above closes this very imperfect sketch of the growth of 
ce conception of affinity, but it ignores the important dynamic 
problem connected with it. Let us turn our attention to 
the questions of force and energy which form so important a 
part in the history of every chemical change 
TL. QuantirativE MreasurEMENTS OF AFFINITY. 
The earliest attempts to measure the strength of affinity 
appear to be those of Geoffrey and Bergmann by arranging the 
several bases in the order in which shes combined with a given 
acid, or as we should now say, in the order in which they 
reaction arbitrarily chosen, and that the strength of absent 
as shown by the order in which the bases were arranged, 
vavtuble | and depended on the nature of the acid selected. 
T tables were amplified and improve oung and 
in the two kinds of union, atomic and molecular, still his pro- 
position could not be considered an important contribution to 
the theory of affinity while it rests for its validity on the lan- 
guage of the atomic theory. The proof of this conclusion will 
e evident when we consider that the same discrimination 
tween the two kinds of chemical union was very clearly fore- 
