90 Dr. Wrightson on the Atomic Weight and 



the latter body being identical with that previously obtained by 

 Williamson from kali-sethylat and iodide of methyle. I need 

 scarcely advert to the double carbonates, oxalates, &c. obtained 

 by Chancel ; because while their formation could be described 

 by similar equations, their rational constitution and atomic 

 weight were not more determinate a priori than those of Wil- 

 liamson's new bodies. It was the absence of this essential ele- 

 ment in the new theory (namely, the establishment of the equiva- 

 lent iccights of the new bodies from which so much was deduced, 

 in accordance with the long accepted equivalent weights of other 

 bodies) which led me to doubt the deductions already detailed 

 of Williamson and Chancel. 



But Williamson, in extending his theory of the alcohols over 

 their respective acids, appeared to me to furnish a hint for more 

 rigid experimental proof. Hitherto the ( othyle ' theory has 

 remained uncriticised : some chemists, evidently dazzled by the 

 apparently very simple interpretation which it affords for a 

 number of phenomena, have taken it for granted without further 

 question ; others, more cautious, appear to wait the result of more 

 extended experiment. It was under these circumstances, that, 

 with the advice of Prof. Kolbe, I undertook the present investi- 

 gation, which appeared to promise in its results conclusive evi- 

 dence upon the question at issue, viz. whether, of two atoms of 

 hydrogen when combined with another element, generally, as 

 for example, when combined with one equiv. of in water or with 

 due equiv. of CI in hydrochloric acid, either or both of these atoms 

 can be replaced by another simple element or by a compound 

 organic radical. A direct proof of this would appear to me a 

 powerful argument in favour of the new theory of the alcohols 

 and aethers. Before describing my experiments, it will be neces- 

 sary for me to refer more particularly to Williamson's theory of 

 the alcohol acids, and to show from certain known facts that it 

 is untenable. Before the proof which Williamson derives for 

 his view of acetic acid from the formation of valeracetone (by 

 distillation of a mixture of acetate and valerianate of potash) can 

 be considered at all conclusive, we must possess more certain 

 knowledge as to the rational constitution of acetone itself than 

 at present, while its equivalent weight is so doubtful. Neither 

 must we forget that the formation and constitution of valeracetone 

 can be represented in several ways. 



Williamson, in assuming the rational formula of hydrated 



C 2 h 3 1 

 acetic acid to be , > with half the usual atomic weight, 



appears to have entirely overlooked the experiments of Kolbe* 



and Frankland upon the decomposition of acetate of potash by 



* Annalen der Chemie, vol. lxv. p. 288 ; vol. lxix. p. 257. 



