M. Geuthev on Glycol. 297 



paration of propylc-glycol and of lactic acid is propylene gaSj 

 which may be prepared from purely inorganic materials. 



Amylc-glycol* is prepared in a similar manner. The ace- 

 tate of amylc-glycol is first prepared by acting upon bromide 

 of amylene with acetate of silver ; and, from the acetate, amyle- 

 glycol is obtained by the action of potash. When pure it is a 

 colourless, syrupy, bitter liquid, becoming viscous at low tempe- 

 ratures. Its specific gravity (0'987) is lower than that of propyle- 

 glycol. It boils at 177^^ C., and distils without decomposition; 

 and it is remarkable that its boiling-jioint is lower than that of 

 propyle-glycol, which, again, is below ethyle-glycol. Treated with 

 niti'ic acidt it is rapidly oxidized, and an acid is formed having 

 the formula C^ H^ 0^, which Wurtz names butylactic acid. It is 

 the third term in the lactic acid series, which now consists of gly- 

 colicacid,C'iH^O«; lactic acid, C«H«0«; butylactic acid, C^ IP 0«. 

 Probably Icucic acid, C'^tP'^O'', is a member of this series. 



The acetate of glycol has the same composition as a combina- 

 tion of two equivalents of anhydrous acetic acid with one equi- 

 valent of aldehyde, 



p4 XJ4 02 f ^^ ^^^ 0^ _ C"* H'* \ni . 



K. n u ^e4H3 03-(C4H3 02)2/^ ' 



and from theoretical considerations Geuther J was led to consider 

 this to be the constitution of the body. Geuther sought to verify 

 this supposition experimentally by heating together one equiva- 

 lent of aldehyde and two equivalents of anhydrous acetic acid in 

 a closed tube to a temperature of 180° C. After keeping the 

 tube for twelve hours at this temperature, it was opened and its 

 contents submitted to fractional rectification. Besides uncom- 

 bincd aldehyde and anhydrous acetic acid, a substance was pre- 

 sent which, after being washed with water, dried, and rectified, 

 was found to have a constant boiling-point of 169^ C. On ana- 

 lysis it had the same composition as acetate of glycol. It is, 

 however, only isomeric with that body; for, besides the fact that 

 its boiling-])oint is 20 degrees lower, its other properties are 

 different. It has an alliaceous odour, and it appears to acidify 

 by repeated rectification. Treated with potash it yields acetate 

 of potash, and an odour is perceptible which is like that produced 

 when aldehyde alone is treated with potash. 



Anhydrous succinic and benzoic acids seem to form similar 

 compounds with aldehyde ; and anhydrous acetic acid forms with 

 benzoic aldehyde a definite couii)ound, with the study of which 

 the aiithor is at present engaged. 



In an investigation of the acids contained in croton oil, 



* Comptes Rendus, vol. xlvi. p. 244, f Ibid. June 21, 1858. 



X Liebig's Annalen, March and May 1858. 



