Sadtler.J OlO [Sept. 17, 



opinion as to whether the acid named is the one possessing the normal 

 molecular structure given above, or is only an isomer of it, having its 

 carbon atoms differently united. Notably with glyceric acid is this yet 

 an open question. Some results lately obtained in the course of a study 

 of this acid appear to me to be of value for the solution of this question. 

 The other view of the molecular structure of glyceric acid makes it 

 unsymmetrical, two of the carbon atoms being doubly united. The 

 formula given is CHj.OH. 



/C.OH 

 O I 

 \CH.OH. 



As will be seen, this formula does not contain the Carboxyl group 

 hitherto supposed to be the invariable characteristic of an organic acid. 

 The author of this theory is Prof. Wislicenus, of Wiirzburg, and the 

 following are the reasons given in support of it. If lactic acid be 

 acted upon with hydrogen iodide, a iodo-propionic acid is formed, 

 according to the following reaction : 



CH3 CH3 



CH.OH + HI = bfl.I + H.OH 



(JO.OH bo.OH. 



This when heated to 150° with strong HI is changed into propionic 

 acid. If, on the other hand, glyceric acid be acted upon with hydrogen 

 iodide, /? iodo-propionic acid is formed. If this had the formula 



CH,I 



CH2 



(JO.OH, 



on treatment with moist silver oxide, it would pass into ethylene lactic 



acid. It does not, however, do this, but a new acid isomeric with 



ethylene lactic acid is formed — hydracrylic — 



CH2.OH 



/(JH 

 I 

 \CH.OH. 



That the molecular structure of this acid is essentially different from 

 that of ethylene lactic acid is proved by the oxydation products of the 

 ■two. Ethylene lactic acid yields malonic acid, while hydracrylic does 

 not yield a trace of this, breaking up into glycolic and oxalic acids and 

 carbonic dioxide. Moreover, hydracrylic acid on heating yields acrylic 

 acid, a derivative of allyl alcohol, instead of the lactid yielded by the 

 lactic acids. 



Prof Wislicenus, however, frankly gives one experiment made by him- 

 self, the result of which tends the other way. He reduced the [i iodo- 

 propionic acid by sodium amalgam and obtained what appeared to be the 

 normal propionic acid, showing the regular molecular structure. 



