SYNTHETICAL EBSEAECHE8 ON ACIDS OF THE LACTIC SEKIES. 351 



No. 1. No. 2. No. 3. 



Or, expressed symbolically, 

 No.l. 



fCMeHHo 

 Ho 



No. 2. 



JCM( 



Ico: 



icn^Uo 



or 



rCHaHo 

 COHo 



No. 3. 

 (CHaMeo 



|UH 

 (CO 



Ho 



(CH2(COHo)' 



All the acids represented by the above formulae are known. The first expresses the 



constitution of lactic acid, which belongs to the normal division j '^ ■"• J^. ±lo q£ ^.j^g 



\(COHo / 



series described at page 345, the second shows the atomic arrangement of paralactic 

 acid, whilst the third represents methyl-glycoUic acid. The proof that the first two 

 of these acids are so constituted, is afforded by the beautiful synthetic processes for 

 their production devised by Wislicenus* and LiPPMANNf. The first of these chemists 

 has shown, namely, that ethylidene cyanhydrate is converted by ebullition with potash 

 into a salt of lactic acid, whilst ethylene cyanhydrate is transformed under similar 

 circumstances into paralactic acid. Lippmann has also shown that by the action of 

 phosgene gas upon ethylene, paralactic acid is produced. Now the formation of ethy- 

 lidene, or rather of its compounds, scarcely leaves a doubt that this body, if isolated, 

 would have the following atomic constitution : — 



or 



CH3 

 H 



{0 



it would consist of an atom of methyl united with an atom of carbon, two of whose bonds 

 satisfy each other. Thus the formation of ethylidene dichloride from aldehyde and 

 phosphoric chloride takes place as follows : — 



* Ann. der Ch. und Pharm. Bd. cxxviii. 8. 1. 



t Ibid. Bd. cxxix. S. 81. Cktim Brown has already pointed out this relation between lactic and paralactic 

 acids, as well as the formula of ethylene given below. — Edinburgh Phil. Trans, for 1864, p. 712. 



3b2 



