CHEMISTRY: T. B. JOHNSON 
69 
sonal equation, in that it is unmistakably influenced by previous experi- 
ence. The correlations between the number of previous trials within 
the period and steadiness of judgment and between the number of 
previous periods of experience and steadiness of judgment are numer- 
ically low, but almost without exception indicate that as experience 
becomes greater the scatter of the individual estimates about their 
mean value becomes less. Probably the rate of this change is not uni- 
form, but is most rapid at first and then falls off. 
The full data and discussion are appearing in two papers in the 
Psychological Review. 
POLYPEPTIDE-HYDANTOINS 
By Treat B. Johnson 
SHEFHELD SCIENTIFIC SCHOOL. YALE UNIVERSITY 
Rec«ived by the Academy. December 24. 1915 
Carbon dioxide is one of the products of decomposition when certain 
proteins undergo hydrolysis, under normal conditions, by digestion with 
aqueous solutions of acids and alkahs. Morner^ observed the formation 
of this acid anhydride during an investigation of the action of hydro- 
chloric acid (sp. gr. 1.124) on horn at 92°, but no quantitative determi- 
nation of the gas was made and no special significance attributed by him 
to its formation. Lippich^ confirmed this observation several years 
later and showed that this anhydride is a normal product of hydrol- 
ysis of other proteins. He also made the important observation that 
the quantity actually formed is dependent on the nature of the hydro- 
iytic agent employed. Quantitative determinations of the amount of 
the gas evolved from several proteins under specific conditions revealed 
the interesting fact that the maximum quantity is obtained when an 
alkaK, as potassium or barium hydroxide, is used as the hydrolytic 
agent. In no case did Lippich fail to detect the presence of this sub- 
stance among his products of hydrolysis. The actual percentages 
obtained by hydrolysis of five different proteins with potassium hy- 
droxide solution are recorded in Table I. 
For his acid hydrolyses Lippich used 33% sulphuric acid. When 
these same proteins were broken down by heating with this reagent 
entirely different analytical results were obtained. The combinations 
in the proteins productive of carbon dioxide were more resistant to hydro- 
lytic changes, under these conditions, and the maximum amount of this 
gas was not obtained until after 25-27 hours digestion. The percentages 
found are recorded in Table I. 
