CHEMICAL SUBSTANCES BY MEANS OF GENERIC RADICALS. 337 



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©-©-©I© and if we write oxalic acid (S) 2 , thus ©Z©-©Z© it is plain that 



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the acids of the lactic acid series may be derived from it by replacing 0" by R 2 . 



Kolbe long ago suggested, and Maxwell Simpson has since proved, that 

 the dibasic and tribasic carbon acids are related to two and three molecules 

 respective of carbonic acid, in the same way as the monobasic acids are to one 

 molecule of the same substance. They therefore contain the radical H two and 

 three times respectively. Similarly, we might expect to find bodies containing 

 the derived radicals (COH*), (CH 2 HO), &c, two or three times, forming thus 

 diatomic and triatomic aldehydes, alcohols, &c. We only know one diatomic 

 aldehyde, glyoxal (COH) 2 , and with certainty, only one diatomic true alcohol, 

 glycol (CH 2 HO) 2 . From the way in which the other glycols are formed, it will 

 be seen, that if the view of the structure of the olefines suggested above be correct, 



HO ) 



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they contain the radical V^ (cV/h) (formed by replacing Br by HO in 



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which again is formed by the direct addition of Br 2 , to © ©~©), and it is 



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 only when this radical is united to H that the glycol can be a true alcohol on 



both sides. Taking this view, propylenic glycol is a compound of the radicals 

 (H©)', and (CH 8 ©)' ; amylenic glycol of (H©)' and (C 3 H 7 0y, and so of the others, 

 one of the atoms of water residue being in the position of the HO in a true alcohol, 

 the other in that of an olefine-hydrate. Of course, it is quite conceivable, and 

 indeed very likely, that there are bodies which contain the radical (CH 2 HO) 

 twice or oftner, and are thus polyatomic true alcohols ; but, with the exception of 

 ethylenic glycol, they are as yet unknown. In treating of diatomic alcohols, we 

 cannot pass over the curious body obtained by Wurtz, by the addition of water to 

 allyl. A consideration of the chemical relations of acrylic acid, acrolein and 

 allylic alcohol to propionic acid, propionic aldehyde and propylic alcohol indicates 



f °\Sormu?a h01 ©"©-C^-©-© and for allyl 0-©-©- 

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It is therefore a diatomic olefine, containing the radical (C a H a y twice, and if its 



