614 Prof. R. A. Lehfeldt on the Electrochemical 
As already observed in the experiments described, the 
activity of the cathode was always greater than that of the 
anode. 
It was found that when the plates were fixed at a distance 
of 4 cms. from the actinium, the ratio of the activity of the 
cathode to that of the anode was about 5 to 1 ; on bringing 
the plates nearer to the actinium this ratio rapidly increased, 
and when the distance was reduced to 2 rams, the activity 
of the cathode was more than a hundred times that of the 
anode. 
These observations and others of a similar nature at 
different pressures (details of which it is hoped will appear 
in a future number), indicate that the sign of the electrical 
charge exhibited by the active deposit particles is some 
function of the distance which they have travelled through 
the containing gas, before reaching the electrodes. 
LYII. The Electrochemical Equivalents of Oxygen and Hy- 
drogen, By R. A. Lehfeldt, D.Sc, Professor of Physics 
at the Transvaal University College *. 
THE present investigation is an attempt (a) to design a 
gas-coulometer (voltameter) suitable for exact mea- 
surement; (b) to find how far the electrolysis of various 
solutions gives the calculated yield of gas ; (c) to use the 
instrument to determine the electrochemical equivalents of 
oxygen and hydrogen. 
In its general design the coulometer follows the accepted 
methods of gas-analysis. 
Description of Apparatus. 
The coulometer itself is shown in fig. 1. It is made 
entirely of glass. The tube A, in which the electrolysis 
takes place, is about 22 mm. diam. and 70 long. It is 
closed below by a rubber stopper B carrying the electrodes 
C and D and the inverted thermometer E. The electrodes 
are of platinum, usually about 3 sq. cms. each, welded to 
platinum wires which are sealed through the glass tubes. 
The tubes are about half a millimetre in internal diameter, 
with an enlargement at the top where the platinum wire is 
sealed through ; they can consequently hold mercury even 
when inverted, and current can be led in and out by means 
of copper wires (No. 30 gauge) pushed up from below. 
The thermometer E is required for the temperature of the 
* Communicated by the Author. 
