398 THE POPULAR SCIENCE MONTHLY. 



these facts, he constructed formulae for all compounds, which formulae 

 were made up of two parts, or radicles. The idea of compound radi- 

 cles was thus closely associated with the dualistic theories of the Ber- 

 zelian school. The new school, led by Dumas, finding dualism insuffi- 

 cient to explain many weighty facts, naturally waged war against the 

 fundamental conception of compound radicles, but they were soon 

 obliged to accept the essential truth of the theory which they at first 

 opposed. Liebig and Wohler's research on oil of bitter almonds led 

 to the discovery of a number of compounds, exhibiting many general 

 analogies, which could best be explained by supposing the existence 

 in each of a compound radicle, or group of atoms. When it became 

 necessary once more to adopt the idea of compound radicles, the theory 

 of substitution was found to be strengthened, not weakened, thereby. 

 Many reactions were made clear by supposing that an element might 

 be substituted by a group of elementary atoms, by a compound radicle. 

 But in adopting the idea of compound radicles the substitutionist yet 

 maintained tbat the chemical compound was a distinct whole, made up 

 of parts he admitted, but, nevertheless, having these parts so modified 

 and merged in one another that the resultant acted as an homogeneous 

 compound. Thus, when the new school likened the ethers to the me- 

 tallic oxides, they did not mean to assert that the molecule of ether 

 was composed of two parts, ethyl and oxygen, held together by elec- 

 tric bonds, and ready to part company without difficulty ; nor, in as- 

 serting that ether was one substance, and not a dualistic system, did 

 they deny the existence of a structure within the molecule of ether. 

 They admitted the existence of a closer relationship between the atoms 

 of carbon and hydrogen constituting the group ethyl than between 

 these atoms and those of oxygen, and they generalized the reactions 

 and analogies of ether, by saying that it might be regarded as sodium 

 oxide in which both sodium-atoms had been substituted by two com- 

 pound atoms of ethyl. Berzelius had himself likened the ethers to 

 oxide of potassium, and by doing this the great apostle of dualism 

 had paved the way for the advance of the unitary theory. 



That portion of the dualistic doctrine which was embodied in the 

 theory of compound radicles was adopted by the unitary schools, but 

 adopted in a modified form ; the effects of this modification were not 

 long in making themselves felt. 



Berzelius, in his later works, had been ready to give a dualistic 

 formula to any compound without stopping to inquire into the facts 

 known about that compound ; he had tended to forsake the only true 

 scientific method, and to substitute the vagaries of his fancy for the 

 facts of nature. The new school averred tbat " compound radicle " 

 was an expression generalizing a class of facts ; that the reactions of 

 bodies were most simply explained by supposing tbat when acted on 

 by chemical force the little parts of these bodies behaved as having a 

 definite structure ; and that therefore the formula of a given body 



