552 JEAN-BAPTISTE-ANDRr5 DUMAS. 



scarcely understand the pertinacity with wliich this innovation was 

 resisted." * 



But if this investigation of gas and vapor densities brought a great 

 strain upon the dualistic system, the second of the three great investi- 

 gations of Dumas, to whicli we have referred, led to its complete 

 overthrow. The experimental results of this investigation would not 

 be regarded at the present day as remarkable, and cannot be compared 

 either in breadth or intricacy with the results of numerous investiga- 

 tions of a similar character which have since been made. The most 

 important of these results were the substitution products obtained by 

 the action of chlorine gas on acetic acid. They were published in a 

 series of papers entitled " Sur les Types Chimiques," and the capital 

 point made was that chlorine could be substituted in acetic acid for a 

 large part of the hydrogen without destroying the acid relations of the 

 product; and the inference was, that the qualities of a compoinid sub- 

 stance depend not simply on the nature of the elements of which it 

 consists, but also on the manner or type according to which these 

 elements are combined. 



To the chemists of the present day these results and inferences seem 

 so natural that it is dilRcuIt to understand the spirit with wliich they 

 were received forty years ago. But it must be remembered that at 

 that time the conceptions of chemists were wholly moulded in the dual- 

 istic system. It was thought that chemical action depended upon the 

 antagonism between metals and metalloids, bases and acids, acid sails 

 and basic salts, and that the qualities of the products resulted from the 

 blending of such opposite virtues. That chlorine should unite with 

 hydrogen was natural, for no two substances could be more unlike ; 

 but that chlorine should supply the place of hydrogen in a chemical 

 compound was a conception which the dualists scouted as absurd. 

 Even Liebig, the " fiither of Organic Chemistry," warmly contro- 

 verted the interpretation which Dumas had given to the facts he had 

 discovered. Liebig himself had successfully investigated the chemical 

 relations of a large class of organic products. He had, however, 

 worked on the lines of the dualistic system, showing that organic 

 substances might be classed with similar inorganic substances, if we 

 assume that certain groups of atoms, which he called " compound 

 radicals," might take the place of elementary substances. In the edi- 

 tion of the organic part of Turner's Chemistry bearing his name. Or- 

 ganic Chemistry is defined as the " Chemistry of Compound Radicals," 



* Hofinaiin, loc. cit. 



