804 
3. Hepertments with acetate-mirtures. A solution of sodium acetate 
(170 gr. per liter) was mixed with different quantities of 1 °/, acetic 
acid. The following experiments were made: 
6th Series of experiments. Enzyme R. diluted with 3 vol. of water 
Peo SiAcahic| | 
| Acetate | acid H,O} Amy- | En- Aros Rotation 
Nr. solution — solut- | lum |zyme) Gr lodine reaction | Py 
ole lm el Clea). Ce. CC: Gan minutes | 
| u 
CIE: 
la Pe 20) 20. SON 200 2 | 47.60 | turbid blue (1.297 
2 20 1 |29 | 200 2 137,65 | 202 blue, shade of violet 6.65 
BAR eas kl Dec ae, 200), (ea) ea GB 400 bluish-violet 6.55 
A || 8 20 4 |26 | 200 2 | 221.05| 198 | bluish-violet (6.21 
5| 20 5.6 |24.4| 200 | 2 | 222.05) 195 violet-blue 6.106 
6 20 7 (23 | ‘200 2 | 221.55 | 197 violet-blue 5.98 
ie ame 12 |18 | 200 2 | 200.05 199 bluish-violet 5.78 
8 20 30 |0 | 200 2 | 118.20 | 200 blue 5.37 
Again an optimal reaction is evolved; it is equal to that of the 
phosphate solutions. On either side of it the action of the enzyme 
diminishes, first slowly, then rapidly. The optinial reaction lies in 
phosphate solutions at py = 6.05, as may be seen from a graphic 
representation of the reduction as function of the py. In acetate 
solutions we find py = 6.08, whereas in citrate-experiments values 
vary according to the concentration. In the 5th series we found an 
optimal reaction py = 654. 
All values of py communicated thus far, were estimated at 18°. 
They are somewhat different at 37°, the temperature at which the 
experiments were made. The reactions of the fluids, that were opti- 
mal, have also been determined by us. We found : 
in the phosphate solutions py = 6.00 
in the citrate solutions (10 c.c. of citrate 4" series) py — 6.86 
in the acetate solutions py= 6.028. 
The neutral point lies at 37° at py = 6.796. 
For purposes of comparing the action of the various regulating- 
mixtures we carried out the following experiment. -(p. 805). 
It is evident from this test that, the reaction being neutral, the 
influence of phosphate is inhibitory; when the reaction is slightly 
acid (pyr 6.5; a neutral reaction is not easily obtained with citrate) 
