Dr. W. Odling on the Doctrine of Equivalents. 43 



doctrine of mult-equivalent radicals, to which I believe I was the 

 first to direct attention some three years ago*. In a lecture 

 delivered at the Royal Institution, I contended that certain 

 chemical compounds, more particularly the hydrocarbons, did 

 not each contain some one special, pre-forraed, self-existent, com- 

 pound radical, but might be considered to contain exactly as 

 many compound radicals as they contained atoms of hydrogen ; 

 and that the abstraction of one atom of hydrogen left a mono- 

 basic radical, of two atoms of hydrogen a bibasic radical, and of 

 three atoms of hydrogen a tribasic radical, and so on. I showed 

 that marsh-gas contained a monobasic radical, methyle ; a bibasic 

 radical, methylene ; a tribasic radical, formyle ; and a quadribasic 

 radical, carbon ; as instanced by its chloro-derivatives, the chlo- 

 ride of methyle, the bichloride of methylene, the terchloride 

 of formyle, and the tetrachloride (bichloride) of carbon; and I 

 contended that in " benzine there was no more reason for believ- 

 ing in the existence of the monobasic radical, pheiiyle, C^ IP, than 

 there was for believing in the bibasic and tribasic radicals C^' IP 

 and C^ H^ respectively," as illustrated in the following Tables : — 

 Muriatic acid H CI 



Water . . 

 Ammonia . 

 Marsh-gas 



H.OH 



(Eurhyzeue). 



H . NH2 



(Amidogen). 



H.CH3 



(Methyle). 



H^O 



H2 



H^ 



NH 



(Imidogen). 



CIP 



(Methylene). 



And in reference to the phenine derivatives — 



HgCl 

 HgAd 



PtCl^ 

 PtAd^ 



H^CH H^C. 



(Formyle). 



AuCP 

 AuAd^ 



C6 H^ . H 



(Benzine). 



C^ H* . CI 

 (Chloride of Phenyle). 



C6 H* . Br 

 (Bromide of Phenyle). 



C« H5 . Ad 



(Aniline). 



C6H^X 



(Nitro-benzine). 



C« H-* . H2 



(Benzine). 



C^H^Ad^ 



(Semi-benzidine). 



C^ IP . X2 



(Dinitro-benzine). 



C^H^XAd 



(Nitraniline). 



C« IP . CI Ad 



(Chloraniline). _ ^ 



For my own p;irt I did not then, and do not now, attach any 

 great imjjortance to compound radicals, whether moiioatomic 

 or polyatomic, as representatives of the actual constitutiun of 

 * " On file Ilyilrocarbons," Journal of tlic Royal Institiitiou, 1855. 



C«H3.H3 



(Benzine). 



C« H3 . CP 



(Trichloro-benziue). 



C«H3.Ad2X 



(Nitro-semibenzidine). 



C6IP.AdX2 



(Di-nitraniline). 



C6H3.X2C1 



( Dinitro-chloro-benzine) . 



