350 MESSES. E. FEANKLAND AND B. F. DUPPA'S 



An inspection of this formula shows that glycoUic acid admits of no isomeric raodifi- 

 fcation, except with a total change of type, unless a different value be assigned to the 

 individual bonds of an atom of carbon. The part of the formula below the dotted line 

 represents oxatyl, which, as we have already shown, cannot be altered without sacrificing 

 the acid character of the compound ; there remains therefore only the part of the formula 

 above the dotted line, which admits of the following modification : — 



The acid represented by the formula so modified no longer comes within our defini- 

 tion of the lactic series. It is carbomethylic acid, and differs essentially from glycollic 

 acid and the lactic series in general, inasmuch as the carbon of its chlorous radical, 

 oxatyl, is linked to the carbon of the basylous radical by oxygen *. 



There being no decisive evidence that homolactic acid differs from glycollic acid, 

 experiment and theory both agree in asserting that the formula Cg H4 O3 represents only 

 one acid in the lactic series. 



Proceeding now one step higher in this series, we have in the formula of lactic acid an 

 expression capable of the following three variations without quitting the lactic type : — 



and we therefore think that the use of these formulffi, where constitutional expressions are intended, will greatly 

 tend to clearness and precision. It is scarcely necessary to repeat Ceum Beown's remark, that such formulae 

 are not meant to indicate the physical, hut merely the chemical position of the atoms. For the purpose of rendering 

 the grajjhic more easy of comparison with symbolic formulae, we have sometimes dissected the former into their 

 constituent radicals hy dotted lines, as above. This dissection, whilst assisting the eye in reading the formulae, 

 cannot fail to suggest the, for the most part, purely conventional character of such radicals. 



• Bearing this constitution of carbomethylic acid in mind, we have only to go one step further in order to 

 perceive the constitution of carbonic acid itself, and the anomalous basicity of that acid ; for if, in the above 

 graphic formula, for carbomethylic acid we replace the methyl by hydrogen, we have 



)-© 



Carbomethylic acid. Carbonic acid. 



It is thus evident that our radical oxatyl, when united with hydroxyl, has sufficient chlorous power to produce a 

 feebly dibasic acid, but inasmuch as carbonic acid is not included in the category of organic acids, it forms no 

 exception to the law above enunciated. 



