52 THE ADVANCE OF SCIENCE 



proved to be of great value ; not only was 

 the search for evidence of diversity of 

 molecular structure successful, but the 

 study of the process of taking to pieces 

 led to the discovery of the way to put to- 

 gether ; and vast numbers of compounds, 

 some of them previously known only as 

 products of the living economy, have thus 

 been artificially constructed. Chemical 

 work, at the present day, is, to a large 

 extent, synthetic or creative — that is to 

 say, the chemist determines, theoretical- 

 ly, that certain non-existent compounds 

 ought to be producible, and he proceeds 

 to produce them. 



It is largely because the chemical the- 

 ory and practice of our epoch have passed 

 into this deductive and synthetic stage, 

 that they are entitled to the name of the 

 'New Chemistry' which they commonly 

 receive. But this new chemistry has 

 grown up by the help of hypotheses, such 

 as those of Dalton and of Avogadro, and 



