LECTURE XIII.] HISTORY OF CHEMISTRY. 261 



as well as its relation to glycol and also to acetic acid. A few 

 years later, Kekule proved, by the action of hydrobromic acid 

 on these acids, 36 that they are converted by this reagent into the 

 corresponding bromides just as readily as the alcohols are ; and 

 thus the views which he had previously stated regarding the 

 existence of " alcoholic hydrogen " in these compounds received 

 new support. Perkin 37 had already tried to confirm the 

 alcoholic nature of glycollic and lactic acids, from the fact that 

 sodium acts upon lactic ether with the evolution of hydrogen, 

 and from the formation of ethereal compounds and the evolu- 

 tion of hydrochloric acid when the acids are treated with 

 acetyl chloride or succinyl chloride. These investigations of 

 glycollic and of lactic acids are also highly important, because 

 it was in connection with them that proof was furnished of the 

 specially noteworthy circumstance that a two-fold function may 

 be ascribed to one and the same substance, the two sets of 

 properties in such a case being simply superadded. 



Kekule was also able to explain the fact that carbonic acid, 

 which is homologous with glycollic acid, is a dibasic acid and 

 forms salts with two atoms of metal. The formula of the 



OH 

 hypothetical hydrate became CO ; both hydrogen atoms 



OH 



were equally influenced by the oxygen, and there was no reason 

 for any difference between them. 38 



It must be specially pointed out here that Kolbe's formula 

 for glycollic acid possesses a great similarity to the one that 

 has just been given, when the signification is alone taken into 

 account and not the form ; it was due, no doubt, to his some- 

 what more complicated mode of writing the formula that Kolbe 

 did not deduce from it all the consequences which it involved. 

 On the whole, the advantages of Kolbe's way of regarding com- 

 pounds were now about to become more manifest. In 1862, 

 by the addition of hydrogen to acetone, Friedel obtained a 



36 Annalen. 130, n. 37 Zeitschrift fiir Chemie. 4, 161. & Kekule, 

 Lehrbuch. i, 739. 



