466 Boyal Society : — 



Since both acids are easily oxidized, the one to carbonic, and the 

 other to oxahc acid, we may say that, with regard to composition, 

 formic acid stands to carbonic acid in a similar relation as glyoxylic 

 acid does to oxaHc acid, 



CO + H,0=CH,0, C,0, + II,0=C,H,03 



Formic acid. Glyoxylic acid. 



Carbonic acid Oxalic acid, 



plus water. 



But with regard to other properties, these acids do not correspond 

 to each other : thus formic acid is monobasic and carbonic acid biba- 

 sic, whilst both glyoxylic and oxalic acids are biatomic. Further, 

 the latter two are derived from the same alcohol, which is not the 

 case with carbonic and formic acids. Amongst the products of the 

 oxidation of glycol occurs also glycolic acid, which is produced from 

 glyoxal by the assimilation of water. 



C,H,0, + H,0=C,H,03 



Glyoxal. Glycolic acid. 



Some regard glycolic acid (C^ H^ O3) as a bibasic acid. According 

 to this view, it would stand to glycol as acetic acid does to common 

 alcohol. .C,H,0, aH„0 



Glycol. 



C^^3 



Glycolic acid. Acetic acid. 



But with this view the capacity of saturation of glycolic acid does 

 not agree. For according to our present experience, if we adopt the 

 formula C^ Hj O3, it evidently combines only with one atom of base. 

 Before we have discovered compounds represented by the general 

 expression C^ H, M^Oj, I think we are not justified in placing glycolic 

 acid in the same relation to glycol as we do acetic acid to common 

 alcohol. According to our present knowledge, this position must be 

 assigned to oxalic acid. 



We can represent to our minds the derivation of glycolic acid 

 from acetic acid in the following manner. If in acetic acid one atom 

 of hydrogen be replaced by peroxide of hydrogen, we obtain a body 

 which has the composition of glycolic acid. 



C2 H^ O2 = acetic acid. 



C, H3 (HO) O,=glycohc acid. 

 But, according to the following observations, this view appears not 

 to be correct ; for glycolic acid can be formed from glycolide and 

 water, and probably also again can be resolved into these two sub- 

 stances in the same way as lactide and water by their union produce 

 lactic acid, and the decomposition of the latter by heat yields lactide 

 again. If, therefore, peroxide of hydrogen be contained in glycolic 

 acid, it must be present in glycolide. 



If monochlorinated acetate of potash be decomposed, according to 

 Kekule, glycolic acid and glycolide are formed . The formation of the 



