THE PRINCIPLES OP ORGANIC CHEMISTRY 63 

 CH,I 



CH, 



•-2 



COgH 



the iodine being replaced by the group OH, through the action 

 of moist silver oxide, AgOH. 



The constitutional formula of /3-lactic acid is further con- 

 firmed by the fact that on oxidation, as would be expected, the 

 group CHgOH yields finally a carboxyl group COgH, and a 

 dibasic acid known as malonic acid is formed, thus : — 



CHgOH COgH 



CH,+ 02 = CH,+ H,0 



I I 



COgH CO2H 



In the next chapter reference will be made to certain other 

 isomeric varieties of lactic acid which cannot be distinguished 

 by any difference in the products of their reactions or in the 

 methods of their preparation ; the present chapter may, how- 

 ever, fitly end at this point with a few words of summary and 

 emphasis. 



It will have been suf&ciently evident that in such a limited 

 space only a few simple examples have been made use of to 

 illustrate the general principles of the science of organic 

 chemistry. It is of the greatest importance for the proper 

 understanding of any subject involving the use of organic com- 

 pounds, and the expression of the construction of the com- 

 pounds by formulae, that the real meaning of these formulae 

 should be once for all properly understood. For this reason 

 rather disproportionate space has been taken in the endeavour 

 to make clear the meaning and the methods of determining 

 successively molecular weights and molecular formulae. To 



