Kihne and Chittenden—Peptones. 245 
concentrated sulphuric acid. Likewise, the reaction with sulphuric 
acid and glacial acetic must be described as almost unsuccessful. As 
this, however, is nothing other than Pettenkofer’s test for bile acids, 
for which its discoverer has recommended concentrated acetic acid 
as a substitute for sugar, we have also tried the reaction with sugar, 
without however obtaining any better result, particularly not the 
beautiful violet-red which albumin and the albumose bodies give. 
Finally, the poor result of Millon’s reaction with antipeptone, in con- 
trast to the brilliant red obtained with amphopeptone, is also to be 
remarked. To this reaction we shall return later. 
It has already been observed by many investigators that among 
the products of the digestion of albumin, bodies are not infrequently 
met with, which give little or no lead sulphide on boiling with sodium 
hydroxide and lead acetate. This is not at all strange, since the pep- 
tones prepared by us show on analysis less than one per cent. of sul- 
phur, in striking contrast to the albumins and albumose bodies, all of 
which contain much larger percentages. In the gland peptones 
(F, G, H,) the sulphur amounted to only 0°50, 0°31 and 0°57 per cent. 
respectively. The peculiarity of peptones in giving up a part of 
their sulphur when warmed with alkali, apparently stands in no direct 
connection with the percentage amount of sulphur. Indeed, solutions 
of the antipeptones G and H, of which the first possessed the lowest 
percentage of sulphur found, showed no browning with this test, 
and only a trace of it when solid particles of the peptone were heated 
with a concentrated solution of alkali containing lead. But the gland 
peptone (F) not purified by phosphotungstic acid and with only 0°15 
per cent. of sulphur became slightly darkened in solution. On the 
other hand, the purest amphopeptone (B) with 0°77 per cent. of sul- 
phur gave the reaction very faintly, while antipeptone C with 0°73 
per cent. of sulphur gave it very plainly. Probably the reaction is 
not to be attributed to the peptones themselves, but proceeds from 
contamination with an easily decomposed substance containing sul- 
phur, whose removal still depends on chance. 
It may be assumed as completely proved that the rose or violet 
coloration, which the products of pancreatic digestion assume with 
bromine or chlorine water, is due to some special body and not to 
antipeptone. We had previously shown this to be the case with the 
antipeptone obtained by the action of trypsin from antialbumid, 
and have now also found in all antipeptones purified with phospho- 
tungstic acid, the absence of all color on addition of bromine water, 
either in large or small quantity. 
