1910. | with the State of Aggregation of Matter. ive 
Another fraction with the same nitrogen content was prepared from a 
solution of peptone which had been dialysed for three or four days against 
running water. Of this preparation, 23°3 per cent. was precipitable by 
formaldehyde. 
Serves [[,—Fifty grammes of Witte’ s peptone were extracted successively 
with two portions of 500 c.c. hot 70-per-cent. alcohol. The insoluble portion 
(Fraction IIIT) was then washed with cold 70-per-cent. alcohol, and finally 
with absolute alcohol, and then dried on a water bath. It weighed, when dry, 
13°5 grammes. | 
From the hot aqueous alcohol a second fraction (Fraction II) separated on 
cooling ; this was washed with 70-per-cent. alcohol, then with absolute 
alcohol and then dried. Fraction I was the portion soluble in 70-per-cent. 
alcohol. 
These were also dissolved up, and solutions made containing the same 
amount of nitrogen (0°8848 gramme per 100 c.c.). 
To determine the complexity, 10 c.c. of each fraction was treated with 
5 c.c. formaldehyde and then titrated with N/10 sodium hydroxide by 
Sorensen’s method. The following were the quantities of alkali necessary to 
neutralise to phenolphthalein :— 
Fraction I PEAR nS Hae 8°9 c.c. 
a jd eA ee Oh 
% 1G IN cae eee Oe Drees. 
To 10 cc. of each fraction was added 5 c.c. of formaldehyde. 
Fraction I was at first clear, and became turbid after standing. 
cf II gave an immediate precipitate. 
III gave a strong clot almost immediately. 
After standing for 16 hours the precipitates were filtered on and the 
nitrogen was estimated in 10 c.c. of the filtrate. 
The following were the percentages of nitrogen precipitated by form- 
aldehyde :— 
an Aeron: ee are 25°3 per cent. 
7 JIE ee apie eee ae DOE ein inns: 
‘ BIBRA A ee) rob Ral, La, OS: Ontails;. 
These results indicate that the larger part of the formaldehyde precipitate 
is due to the more complex polypeptides contained in the peptone. 
Inhibitory Action of Salts, 
If minute quantities of caustic alkali be added to the peptone solution, no 
precipitate will form on the addition of formaldehyde. The formation takes 
