PROCEEDINGS OF SECTION B. 205 
5.—THE ELECTROLYTIC MANUFACTURE OF CHLORINE. 
By Joun JONES. 
6—SOME PRACTICAL POINTS IN THE PRECIPITATION 
OF GOLD FROM CYANIDE SOLUTIONS BY CHARCOAL. 
By Rosert B. LAms. 
7.—EXPERIMENTS ON THE RELATIVE VELOCITIES OF 
IONS. 
By Orme Masson, M.A., D.Sc. 
[With Plate IV.| 
l.—IntTRopucToRY. 
In a paper published a few months ago by the Royal Society 
of London (Phil. Trans., Vol. 192, p. 331), I gave an account of a 
method for the direct comparison of the speeds of positive and 
negative ions when travelling through a jelly under the influence 
of an electromotive force, and of the results obtained by apply- 
ing the method to the chlorides of potassium, sodium, lithium, 
and ammonium, and to the sulphates of potassium, sodium, 
lithium, and magnesium. In this paper I desire to give a few 
results of further experiments with the same method, but it 
is necessary first to give a brief recapitulation of its essential 
features. 
The solvent employed is water containing sufficient gelatine 
to set, on cooling, to a stiff jelly. Enough of the salt under 
investigation is dissolved in this to give a solution of the re- 
quired strength, say, half-normal. A straight graduated tube 
of convenient length and small bore is filled with the molten 
jelly, allowed to cool, and then fitted at each end, by means of 
caoutchouc stopper, into the side neck of a flask of compara- 
tively large capacity. The whole apparatus is then placed in 
water kept at a constant temperature, through which the 
eraduations of the tube can be read. The flasks contain elec- 
trodes connected by wires with a battery capable of maintain- 
ing a small current at a constant E.M.F. of about 40 volts. 
There are suitable arrangements for indicating the current 
and E.M.F. at any moment. The circuit is closed and the 
experiment started by filling the flasks with certain solutions, 
the nature of which is all-important. The flask containing the 
