DAVIDL. YABROFF, G. E. K. BRANCHAND BERNARD BETTMAN
1850
were designed, however, for a Werent purpose, and are not as well adapted for extrapolation,
Vol. 56
vanadium concentrations were held constant. The value given above is therefore the better. I wish to express my appreciation to Professor William C. Bray, to whom I am indebted for suggesting the problem and for valuable assistance from time to time during its completion.
Summary 1. By observation of the variation of the electromotive force of the cell
with acid concentration and with concentration of pentavalent vanadium, the formula of the pentavalent vanadium ion has been shown to be VO; in acid solution. 2. The data of Coryell and Yost2 for a similar cell have been recalculated, correcting for a small error in acid molality, and shown to be in complete agreement with this result. 3. From the recalculated data of Coryell and Yost, the standard electrode potential for the reaction VO:
which requires systematic dilution from cell to cell of all solutes present, whereas in these,
[CONTRIBUTION FROM
THE
+ 2H+ + e = VO++ + HzO
has been determined as 0.9996 volt. RECEIVED APRIL30, 1934
BERKELEY, CALIF.
CHEMICAL LABORATORY OF THE UNIVERSITY OF CALIFORNIA]
The Relative Strengths of Some Hydrocarbon Derivatives of Boric Acid BY DAVIDL. YABROFF, G. E. K. BRANCH AND BERNARD BETTMAN
Introduction Resonance.-If the group X may act as a donor of electrons in an acid of the type XB(OH)z, then the structure X+=B-(OH)z will be in OH
resonance with the forms XB(OH)z, XB-
