THE PHYSIOLOGICAL EFFECTS oF Ions 459 
effects, and that these are the effects of the hydrogen ions. 
All these acids have quantitatively the same physiological 
effect when the same number of hydrogen ions are contained 
in the unit volume of solvent. 
5. My experiments on the effects of organic acids have 
only just been begun. Thus far I have used only four acids, 
namely, acetic acid, lactic acid, oxalic acid, and malic acid. 
Ten c.c. of a one-tenth normal solution of one of these acids 
were added to 100 c.c. of a 0.7 per cent. NaCl solution. 
The increase in weight expressed in per cent. of the original 
weight of the muscle is given in Table IV: 
TABLE IV 
(V=110) 
I II TIT IV Average 
Acetic ...........244. 4.1% 3.4% 3.3% 4.7% 3.9% 
Da Ctl Gis eves sioacinin ees 6.7 6.8 8.0 8.0 7.4 
ip ORD Giese ceseuavn sea a 6.4 6.3 6.0 8.8 6.9 
4 MAG... ic sece esas 4.0 4.4 5.4 6.8 5.1 
In order to decide whether we are dealing here with the 
effects of H ions, and in how far, we must first determine the 
degree of dissociation of these solutions. We use for this 
purpose Ostwald’s determinations.’ 
For acetic acid, #100 = 15 (about), «0 = 364; 
For lactic acid, «100 = 38 (about), «oo = 358 ; 
For oxalic acid, «200 = 338 (about), «00 = 365 ; 
For malic acid, #200 = 85 (about), » 00 = 356. 
If we calculate from these figures the fraction of mole- 
cules that are dissociated, the following values are found for 
a for the concentrations employed: 
For acetic acid, a= ##; = 0.04; 
For lactic acid, «= #4; = 0.10; 
For oxalic acid, a = $3 = 0.92 ; 
For malic acid, «= 5 = 0.23. 
1 Abhandlungen der Stichsischen Gesellschaft der Wissenschaften, Vol. XV (1889). 
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