112 On the Constitution of Carbon Compounds. 



It will be remembered that, on the strength of the fact that 

 the heat of formation of H — 0=0 in the aldehydes together 

 with that of C=0 in the ketones was found equal to that of 

 0=C — (OH) in the acids, Thomsen arrived at the startling 

 conclusion that the aldehydic radical consists of hydroxyl ; 

 so that 



Aldehyde. Ketone. Acid. 



C— (OH) + 0=0 may be equal to 0=C— (OH). 



Now the introduction of x destroys this equality; for the sum 



of the heat of formation of the aldehydic and ketonic radicals 



x 

 will exceed that of the acid radical by ^, and this excess brings 



the results into full accordance with the generally accepted 

 views concerning the constitution of these bodies. The actions 

 concerned in the formation of these groupings will be 

 Aldehyde. Ketone. Acid. 



0=0— H 0=C 0=0— (OH) 



(0=0) + (C— H) (0=0) (0=0) 4 (C— (OH)). 



But (C — H) has been shown equal to (C — (OH)); and hence 

 the aldehyde + ketone will exceed the acid by (0=0), which 



x 

 quantity, as shown above, will be within 15000 cal. of — . 



2i 



It is important to remark that the value obtained by 

 Thomsen for (=0=0) in the ketones (54250) is by no means 

 identical with that obtained for (0=0) in carbonic oxide 

 (77670), showing that the heat developed is certainly depend- 

 ent on the presence of other atoms in the compound, and not 

 on the number of bonds concerned only. This difference is 

 still further increased if x be introduced into the calculation ; 



x 

 for (=0=0) becomes 54250 + -^ whereas (0=0) becomes 



77670 + .*. * 



A fuller study of Thomsen' s results can scarcely fail to 



bring to light a large number of important conclusions which 



have been omitted here ; and there can be few chemists who 



will not appreciate the services which Professor Armstrong 



has rendered to science in criticising a work of such extreme 



importance, and indicating the direction in which some of the 



apparently anomalous results to which it leads may be brought 



into accordance with views which we cannot afford to reject. 



