Vol. 7, 1921 
CHEMISTRY: MENZIES AND WRIGHT 
77 
aminoacids. The above relationships are expressed by the following 
equations : 
NH — CO 
CO 
NH — CH 2 
(hydantoin) 
NH — CO 
H 2 0 NH 2 CH 2 COOH 
— >■ (glycocoll) 
CO 
CH< 
H 2 0 NH 2 CH 2 CH 2 COOH 
— >- (/3-alanine) 
NH — CH 2 
(hydrouracil) 
Before undertaking our research on catalytic reductions we devised a 
practical machine whereby we might operate on a quantitative basis 
with large quantities of reagents. A description of this machine and a 
complete record of our preliminary work on uracil reduction will be pub- 
lished in a future number of the Journal of the American Chemical Society. 
1 Ber., 45, 1912 (619). 
2 Ibid., 37, 1904 (124) ; 38, 1905 (1398, 1406). 
3 Ibid., 45, 1912 (3579, 3595). 
4 Lengfeld and Stieglitz, Amer. Chem. J., 15, 1893 (221). 
6 /. Biol. Chem., 3, 1907 (183). 
THE APPLICATION OF A DIFFERENTIAL THERMOMETER IN 
EBULLIOSCOPY 
By Alan W. C. Menzies and Sydney L. Wright 
Department of Chemistry, Princeton University 
Communicated by O. Veblen. Read before the Academy, November 17, 1920 
For purposes of molecular weight determination of dissolved substances, 
the ebullioscopic procedure has certain advantages over the method of 
cryoscopy. Since, to use the latter, one must for convenience employ 
solvents whose freezing-points lie at easily accessible temperatures, it 
comes about that water, benzene and acetic acid have been commonly 
preferred. To obtain satisfactory values for the molecular weight of a 
solute, it is best to choose a solvent so alike to it chemically that com- 
pound formation between them shall be at a minimum. To be restricted 
in the choice of solvents is, therefore, a disadvantage. Boiling tempera- 
tures are preferable to freezing temperatures as disfavoring the formation 
of exothermic compounds. A majority of organic compounds boil nor- 
