The Evolution of Chemistry. 139 



radicals, however, that intermarry just as the elements do. 

 If we were as ignorant of their structures as we are of the 

 structures of the elements we would certainly take them to 

 be elements. The hydroxyl group, so common in acids, al- 

 cohols, and metallic hydrates, weds with its own counterpart 

 in peroxide of hydrogen. The cyanogen group does the 

 same in cyanogen gas. The methyl group doubles itself in 

 ethane and the methyenyl in acetylene. There is not a soli- 

 tary feature about the behavior of an element that is not ex- 

 actly repeated in these compound radicals. This coherence 

 in groups of more or less permanence is what makes the evo- 

 lution of chemistry along its lines of present greatest discov- 

 ery possible. 



If complex molecules did not break down in a systematic 

 manner it would be impossible to tell how they were put to- 

 gether. If neither atoms nor molecules exist, as metaphys- 

 ical speculators would have us believe, it is pretty nearly 

 time for them to tell us what it is that acts so much as if 

 they did. In Dalton's days they should have given their 

 theory when the facts were few, and therefore susceptible 

 to many explanations. If they had no explanation, then 

 how can they ever hope to have one now, when the data are a 

 millionf old what they were then ? When we further perceive 

 that very few of these millions of facts could ever have been 

 dreamed of or known without picturing Dalton's atoms as 

 their cause, we see how wild and silly their statements are. 

 The whole field of organic chemistry has been opened up 

 and developed because of our belief in atoms. Our facts 

 were discovered and are now held together by this hypoth- 

 esis. Remove it, and they drop apart like a rope of sand, 

 with not even an explanation of how we ever discovered 

 them. At the beginning of this century everybody held to 

 the vital-principle theory of organic substances. It was 

 counted absurd to imagine for a moment that organic ma- 

 terials could ever be synthetically produced. Wonler, sixty 

 years ago, began the work of discovery in this field. From 

 the synthesis of urea to the synthesis of cocaine is a long 

 stretch through a mazy labyrinth manifoldly more complex 

 and obscure than that in which Ariadne's thread was sup- 

 posed to have been used. Dalton's thread has guided chem- 

 istry. 



In 1827 Gmelin was writing a book on organic chemis- 

 try. This was only at the beginning the first shower, so to 

 speak of the deluge of facts that is now pouring in upon 



