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. (1) 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 : 
O 
/ 1 
/ 0 
0 
/ 1 
c 
-C H 
-c 
-C H 
\ 
\ 
H 
H 
(a) 
(b) 
(a) 
(b) 
The lability, i.e. the kinetic chemical energy in an aide- 
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 form of hydroxyl occupies a volume of 2.3; while in the car¬ 
bonyl form one of 5.5. Also doubly linked carbon atoms have a 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 , R. 
76) from thermo-chemical observations, that aldehydes behave in certain points like com¬ 
pounds containing a hydroxyl-group besides unsalurated carbon ; this would correspond 
to the phase (b) of our inference drawn from a very different contemplation. 
