Kiihne and Chittenden— Peptones. 249 
from peptone) and tested it, both by Millon’s reaction and Piria’s 
test. Further, a few grams of the same preparation were heated for 
several days with six times its weight of sulphuric acid (2 : 3 water), 
and after removing the acid with barium hydroxide, tyrosin and 
leucin were found among the decomposition products. 
Antipeptone was now likewise submitted to the above treatment. 
The method of conducting this experiment with albuminous bodies 
which we have used successfully, even with 2-3 grams of substance, 
is as follows. The substance is placed in a small, strong flask stand- 
ing on an asbestos plate, and five or six times the weight of sulphuric 
acid of the above mentioned strength is added and the mixture kept 
boiling as long as desired. The loss of water by evaporation is pre- 
vented by connecting to the neck of the flask a glass tube 1 metre 
long and 1 centimetre in diameter, so that the lower end cannot be 
closed by a drop of water. The upper end of the tube is drawn out 
to a capillary point and as it does not become warm at the top dur- 
ing the boiling of the fluid, all loss of water is prevented. 
To be as sure as possible, we have treated the antipeptone in this . 
manner for 48 hours. The contents of the flask were then much 
diluted with water, filtered from the sticky residue always present, 
made alkaline with a concentrated solution of barium hydroxide, the 
barium separated from the filtrate by sulphuric acid, after which the 
clear fluid was concentrated and allowed to crystallize. It is not 
advisable to remove the sulphuric acid with barium carbonate, since the 
latter is unavoidably used in excess, for it is very undesirable to have 
the barium precipitate unnecessarily increased in bulk, as the cleay- 
age products of albumin are difficult to remove even with hot water. 
Further, the mixure is made alkaline by barium carbonate and 
soluble barium compounds always appear, which must be removed 
by sulphuric acid in every case. 
In the strongly concentrated solution finally obtained, in case 
leucin and tyrosin have really been formed, as with most albuminous 
bodies, their presence may be readily shown microscopically and 
after suitable separation of the mother liquor, or if necessary, after 
re-crystallization from dilute alcohol, their chemical reactions may 
likewise be obtained. We have succeeded after this manner in showing 
the presence of leucin always in antipeptone ; tyrosin, however, only in 
a few cases, and even then only after repeated crystallization. When- 
ever tyrosin occurred it was in exceedingly small quantities. From 
the antipeptones (gland peptones H and G) with which Millon’s test 
had hitherto failed, tyrosin could not be obtained at all, and that 
TRANS. Conn. AcAD., Vou. VII. 32 Nov., 1886. 
