LECTURE VIII. 



FURTHER DEVELOPMENT OF THE RADICAL THEORY VIEWS CON- 

 CERNING ALCOHOL AND ITS DERIVATIVES PHENOMENA OF SUB- 

 STITUTION DUMAS' RULE THE NUCLEUS THEORY THE 

 EQUIVALENT OF NITROGEN. 



IN the preceding lecture I endeavoured to explain the sig- 

 nificance of the radical, and I shall now deal more fully with 

 its nature. Enough has been said already by way of prepara- 

 tion for the controversies which were called forth by the choice 

 of a definite atomic group as the radical of a compound ; and 

 I now consider it my business to pass in review the most 

 important of the discussions. It was especially with respect to 

 the constitution of alcohol, and of the substances derived from 

 it, that differences of opinion arose. Since it cannot be denied 

 that the opinions regarding these compounds exercised an im- 

 portant influence upon general views, and, further, since the 

 most prominent chemists took part in the discussions, I shall 

 endeavour to show, with respect to this group of substances, 

 how various and how contradictory were the conceptions as to 

 the arrangement of the atoms. 



I dealt, in the preceding lecture, with the so-called etherin 

 theory, which originated in the comparison of the ethers with 

 the salts of ammonia. In that comparison the radical N H 3 was 

 assumed to be present in these salts ; and even although the 

 dualistic tendency of the whole mode of regarding them cannot 

 be disputed, still the view is not in harmony with the other 

 opinions respecting salts. Even then there was another theory 

 as to the compounds of ammonia, in accordance with which 

 they did not occupy any exceptional position, but were looked 

 at from a purely dualistic point of view. 



The radical ammonium, which, as has already been stated, 



