HISTORY OP THE ATOMIC THEORY. 161 



trary, as lie shews us that in double decomposition something 

 always remains unsaturated ; but generally very little remains. 

 One is sorry that being so near a law, he had not the 

 slightest conception of it. The most important part of his 

 work, as far as our purpose is concerned, seems to me to be 

 contained in the following sentences. The title of the work 

 is "The Doctrine of the Affinity of Bodies."* I shall not 

 give the original, although scarce, as the work, from the fact 

 above stated, has lost its great importance. 



In the Preface, he says, " at first my only intention was to 

 make for my own use a treatise which should contain the 

 order of the ascertained affinities and the circumstances under 

 which they acted, lest I should not be able to remember them. 

 But it occurred to me that others might find it useful also, 

 if it were more worked out. For this end I endeavoured to 

 explain the cause and the law of affinity on a good founda- 

 tion, and the circumstances under which the bodies combine as 

 well as the true relation of their weights towards each other. 



Page 4. " It is of itself clear that any combination of bodies 

 must have a constant unchangeable proportion, which can 

 neither be greater nor smaller without some cause acting 

 externally, because, otherwise, nothing certain could be de- 

 cided on by comparing them. It therefore necessarily follows, 

 that every possible combination of two bodies stands in the 

 most exact relationship with every other, and this relation 

 expresses the degree of combination. 



Page 9. " These smallest particles of each body have at all 

 times, in a natural state, a determinate figure; but the whole 

 mass of the body takes a form according as chance or art gives 

 it, without causing any change in the smallest particles, just 

 as the tender fibres or tubes in a piece of wood remain always 

 the same, although the whole piece may be in the shape of a 

 ball or a cube." 



• Carl Friedrich Wenzel, Lehre von der Verwandschaft der Koerper. 

 Dretdeo, 1777. 



Y 



