402 LABILITY AND ENERGY IN RELATION" TO PROTOPLASM. 



plain their ability to react in two different ways ; but both 

 these authors have failed to explain how the continuity of these 

 oscillations is kept up. 



How, then, can the lability of aldehydes be explained by a 

 continuous atomic motion ? The mechanism is in all probability 

 as follows : In the first place there is the hydrogen of the 

 aldehyde group attracted from two sides, that of the oxygen and 

 that of the carbon, the attraction of the former being, under the 

 given conditions, a little superior to that of the latter. 



In the second place, the oxygen atom moves closer to the 

 carbon atom as soon as the doubly linked state in the aldehyde 

 group (a) has passed into the simply linked state (b) of the hydroxyl 

 group. 0 ' This sudden motion of the oxygen atom influences of 

 course also the attached hydrogen atom, whose vibrations in 

 conjunction with the two free valencies of the carbon atom, bring 

 it again close to the carbon. At this moment the oxygen becomes 

 again doubly linked and moves off into greater distance, and the 

 former play commences anew. The condition, therefore, which 

 the above mentioned critic believes to be missing, is actually 

 present, namely : when the hydrogen atom has moved back, 

 passed the mean position, and approximated itself to the oxygen 

 atom, the opposite phase becomes superiorily attractive/ 2 ' Both, 

 the hydrogen atom and the oxygen atom are continuously in a 

 fierce state of vibration, as may be indicated by the following 

 formulae : 



-C -C h -C -C h 



\ \ 

 H H 

 (a) (b) (a) (b) 



The lability, i.e. the kinetic chemical energy in an alde- 

 hyde group, under certain conditions, may reach a much higher 

 intensity. Such a condition is, e.g., the presence of an amido- 

 group in the same molecule. The continuously moving oxygen 



(1) Oxygen, in the f >rm of hydroxyl occupies a volume of 2.3; while in the car- 

 bonyl form one of 5.5. Also doubly linked carbon atoms haven larger molecular volume 

 (and higher thermic value) than simply linked ones. 



(2) Attention may here be called to the inference drawn by Thomson (Ber. 19, K. 

 76) from thcrmo-chemical observations, that aldehydes behave in certain points like com- 

 pounds containing a hydroxyl-group besides un-aturated carbon ; this would correspond 

 to the phase (b) of our inference drawn from a very different contemplation. 



