( 415 ) 
even after drying, of a pure white colour. This was only then not 
the case, when, what occurred a few times, the gastric juice was 
mixed with bile. Gastric juice which, by admixture with bile, was 
distinctly coloured yellow, was never used for the preparation of 
pepsin. But it could be shown that even the smallest traces of bile- 
pigment, were retained by the pepsin. When the gastric juice contained 
but so little of it, that the yellow colour could not clearly be 
distinguished, the pepsin, precipitated from it by dialysis, yet showed 
a yellow tint which became greenish when dried. For analysis I 
have exclusively used entirely colourless pepsin. 
The fluid, separated from pepsin which had been precipitated by 
dialysis, was half saturated with ammoniumsulfate. Thus a not unimpor- 
tant precipitate was again obtained. This was dissolved, when liberated 
from ammoniumsulfate -by dialysis into 0.2 0/, HCI, at 37° C. in 
as little hydrochloric acid as possible of the same strength, filtered 
and subjected to dialysis into distilled water. The substance thus 
precipitated was dried and separately collected for analysis. 
When the pure gastric juice was half saturated with ammonium- 
sulfate, in the filtrate of this no perceptible precipitate could any 
more be produced by complete saturation with this salt. The fluid, 
dialysed for 24 hours, filtered and then half saturated with ammonium 
sulfate, still after total saturation showed a certain amount of turbid- 
ness. When dialysed at a low temperature, a very small portion of 
the substance is always decomposed, whereby albumose is liberated. 
In the first place I have investigated the amount of phosphorus. 
The continued investigation of the pepsin, obtained out of pigs’ 
stomachs, had already made me doubtful, whether the phosphorus 
I found in it, really owed its origin to the highly complicated 
proteid, of which this pepsin principally consists. As I have formerly 
stated the amount of P of my first preparations was about 10/,, but 
already then I observed that a more or less considerable contamination 
with substances ccntaining phosphorus, was likely. The more the 
pepsin was purified, the smaller the amount of phosphorus was 
generally found to be, though I found the pepsin out of the pig’s 
stomach never free from it. Moreover I had become convinced that 
I had erroneously placed the coagulation-product, which is obtained by 
heating of the acid solution of pepsin, on one line with the well- 
known nucleo-proteids. Later on I shall again refer to that. 
I now found the pepsin of the dog free from phosphorus. The 
substance separated by dialysis from the gastric juice, still contained 
a trace of it, but such a small quantity (about 0.01 °/)) as can only 
be attributed to impurity, 
