460 STUDIES IN GENERAL PHYSIOLOGY 
The relative number of dissociated molecules varies con- 
siderably. In the case of oxalic acid it reaches a value 
which approximates almost that for hydrochloric acid. We 
find, also, that the acid effect of oxalic acid approximates 
that of inorganic acids. For 4H,SO,, KHSO,, and NaHSO,, 
when V = 210, we obtain increases in weight which average 
8.6, 7.9, and 8.2 per cent. (see Tables II and III). For 
oxalic acid we find an average of 6.9 per cent. The action 
is somewhat weaker than that of the inorganic acids. We 
may in this, perhaps, already see the effects of the anion. 
In the main, however, we may yet attribute the absorption 
of water under the influence of oxalic acid to the hydrogen 
ions. 
In the case of lactic acid, however, this is out of the ques- 
tion. Only one-tenth of all the molecules were dissociated, 
yet the absorption of water was at least as great as in the 
case of oxalic acid. It is impossible that we are dealing here 
with the mere effects of the H ions of the lactic acid. The 
lactic-acid molecules bring about secondary effects in this 
case which add themselves to the effects of the H ions. 
Acetic acid acts more than half as strongly as oxalic acid, 
and yet only 4 per cent. of all the molecules present are 
dissociated, while 92 per cent. of the oxalic-acid molecules 
are dissociated. The molecules of the acetic acid must there- 
fore have secondary effects, and these in even greater degree 
than in the case of lactic acid, which add themselves to the 
effects of the few H ions which are already present.’ 
Malic acid, finally, is six times as strongly dissociated as 
acetic acid; its activity is, however, only a little greater than 
that of the latter. 
I am not inclined to admit that these apparent irregulari- 
1It is also possible that acetic acid migrates comparatively more rapidly into 
the muscle fiber than oxalic acid. But it is also possible that these acids undergo 
or cause chemical changes in the mascle substance which increase their efficiency. 
[1903] 
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