420 SCIENTIFIC THOUGHT. 



not appear that philosophers considered the existence and 

 usefulness of chemical formulae as a proof of the physical 

 existence of atoms, or of smallest indivisible particles of 

 matter, in the older sense of the theory. Hand in hand 

 with this purely formal and experimental treatment of 

 24. chemical phenomena went the almost absolute neglect 



Neglect of 



th 6 study with which questions referring to chemical affinity were 

 treated. The word was little more than a name for an 

 unknown something. 



How it came to pass that substances had more or less 

 affinity for each other, what was meant by a chemical 

 compound, symbolically expressed by writing two or more 

 letters, near or above each other, in a square or in a circle, 

 united by parentheses or brackets, did not seem to trouble 

 chemical philosophers at all. To compare the problem of 

 chemistry with that of astronomy, the former for a great 

 part of our century resembled that phase of astronomical 

 knowledge in which stellar maps and catalogues, plans of 

 orbits and orreries, were considered sufficient, giving a pic- 

 ture of a certain constellation of the heavenly bodies, but 

 no idea of how these configurations were maintained and 

 altered. In fact, chemistry was for a long time a science 

 purely of numbers, to which was attached a natural his- 

 tory of the substances to which these numbers belonged. 

 The geometrical arrangement of the formulae was usually 

 looked upon as only symbolical : of the dynamical changes 

 which take place in time, and imply the knowledge of 



considered to be represented by 

 more than one number in in- 

 stances where the same metal had 

 several basic or acid oxides, as in 

 the case of nitrogen and phosphorus 

 (ibid., p. 805). Laurent in ' Comptes 



Rendus/1844, vol. xix. p. 1099, says : 

 " Le meme corps simple se presente 

 tantot avec certaines proprie"tes, 

 tantot avec d'autres, il entre dans 

 les corps composes, tantot avec un 

 certain poids, tantot avec un autre." 



