Vol.. 7, 1921 CHEMISTRY; JOHNSON AND BROWN 
75 
by resonance. Thus far, however, I have failed to find more than a pipe 
sounding under slightly increased or slightly diminished pressure. 
Again if the apparatus, figure 3, is made of insulating material (P, j 
removed) and is provided with a disc electrode parallel and coaxial with 
the surface M used as a counter-electrode, the combination becomes 
an absolute electrometer of considerable interest. All the usual experi- 
ments of the electroscope may be performed by means of it, with the po- 
tential readings immediately in absolute units. 
STUDIES ON CATALYSIS. I— THE REDUCTION OF URACIL 
TO HYDROURACIL 
By Treat B. Johnson and Elmer B. Brown 
Department, op Chemistry, Yale University 
Communicated February 1, 1921 
Levene and LaForge, 1 in 1912, made the interesting observation that 
the nucleoside uridine I, which is obtained by hydrolysis of nucleic acid, 
is reduced practically quantitatively to dihydrouridine II by Paal's 2 
method of catalytic reduction, namely, by means of colloidal palladium 
and hydrogen. This transformation involves an addition of hydrogen 
at the double bond joining positions 4 and 5 in the uracil nucleus and the 
change is represented as follows: 
NH — CO 
CO CH H 2 
I II -> 
NH — C — CH'CHOH.CHOHCH.CH 2 OH 
i o 1 
I 
NH — CO 
I I 
CO CH 2 
I I 
NH — CH-CH'CHOHCHOH.CH.CH 2 OH 
i o > 
II 
As far as the writers are aware, this is the first and only case described 
in the literature of the application of a catalytic process of reduction in 
the pyrimidine series. A striking fact revealed by the work of these in- 
vestigators is the remarkable ease with which the sugar can be detached 
from this dihydrouridine molecule II by hydrolysis with acids. The 
corresponding uridine combination I is very stable and resistant to hy- 
drolysis. 
