Dr. E. J. Mills on Isomerism, 5 



plished. The author does not think it likely that in alanine, 

 sarkosine, and lactamide there is any difference between the car- 

 bon, hydrogen, or oxygen as individually considered. He recog- 

 nized, however, the insufficiency of rational formulae to meet 

 the case. 



This deficiency in existing formulae was observed by Butlerow, 

 who altered, or rather extended the current doctrine of atomici- 

 ties, equivalencies, or affinities in a manner which was supposed 

 to satisfy every requirement. He says*, "It is necessary to 

 distinguish the quantity of affinity from its intensity — that 

 is, the smaller or greater energy with which it tends to be- 

 come active. This intensity varies as various substances act on 

 the body, and depends on the conditions under which the action 

 occurs. It appears also that if a part of the affinity of polyato- 

 mic elements, and especially of carbon, has been combined, all 

 the other conditions remaining the same, the residual free affi- 

 nity exhibits another degree of intensity In this man- 

 ner we are led to distinguish primary, secondary, &c. affinity." 

 In the same journal Kekule also advertsf to the inefficiency of 

 typical formulae. He considers that the nature of the hydrogen 

 in certain organic bodies depends on the oxygen it is combined 

 with. More generally it is the other elements which constitute 

 the " chemical nature of the place " occupied by the remaining 

 element. This view appears to be the same, substantially, as 

 that of Butlerow. 



Similar notions were also entertained by ErlenmeyerJ. Speak- 

 ing of such compounds as ammonia and carbonic oxide, he says, 

 " The possibility of their existence can be explained, according 

 to my view, only on the assumption that the different affinities of 

 polyatomic elements are not all endowed with an equal propen- 

 sity to combine with a given element. On the contrary, many 

 facts seem to show that the atoms of one and the same element, 

 when attached by different affinities of a polyatomic element, 

 may exercise different chemical functions" (p. 30). And again, 

 " Supported by facts now known to us, I believe I may venture 

 to express the opinion that there is no such thing as an abso- 

 lutely di- or polybasic acid — that is, an acid in which two or more 

 atoms of hydrogen are possessed of an absolutely equal capability 

 of replacement by metals or substances resembling metals" 

 (p. 222) . From a footnote added here it appears that Kekule's 

 explanation is considered applicable to most of such cases. 

 Further on, in the same volume, Butlerow again developes his 

 doctrine of primary, secondary, &c. affinities (p. 300) . Berthelot 



* Zeitschr. Ch. Pharm. 1861, p. 556. f Ibid, p, 624. 



X Ibid. 1862. 



