144 REPORTS ON THE STATE OF SCIENCE. 
Llectroanalysis—Report of the Committee, consisting of Pro- 
fessor F. §. Kipprna (Chairman), Dr. F. M. PERKIN (Secre- 
tary), Dr. G. T. Bumpy, Dr. T. M. Lowry, Professor W. J. 
Pore, and Dr. H. J. S. SAnp. 
Durine the year experiments have been carried out upon a new 
design of potentiometer, on the general simplification of apparatus and 
method for the electro-deposition of metals particularly by means of 
graded potential; and in connection with the electro-deposition of mer- 
cury upon gold, silver, platinum, and mercury cathodes. 
In connection! with the latter part of the subject it has been found, 
when mercury is deposited on a gold electrode, that the results are 
invariably from 0.5 to 2.0 per cent. too high; the same applies also to 
electrodes of silver. The gold electrode employed was in the form of a 
flag, and had a total active surface of 0.5 square decimeter. As pure 
gold was found too soft for working purposes, an alloy containing 5 per 
cent. of platinum was used. Specially purified mercuric chloride- 
bromide, and sulphate were employed, but the results obtained were 
always too high. When a platinum gauze electrode was placed in series 
with the gold electrode and an identical solution employed, as a rule the 
metal deposited on the platinum was almost theoretically correct, although 
at times it was fractionally low. 
In order to get more rapid deposition the gold electrode was placed 
in the field of a very powerful electro-magnet, but even though the time 
of deposition was reduced by one-tenth the results were still too high. 
The silver cathodes consisted of coils of pure silver within which a 
platinum anode was rotated, but although the whole of the metal was fre- 
quently deposited in forty-five minutes, the results were almost always 
too high. The exact cause of the high results obtained was not ascer- 
tained, although it was at first supposed to be due to occluded hydrogen ; 
this was practically proved not to be the case. It was finally shown that 
the only really satisfactory method for depositing mercury was to use a 
cathode of mercury. A new electrolysing vessel of quartz was designed 
for this purpose. This apparatus is a small quartz beaker capable of 
holding about 80 c.c. of solution, and has a siphon fused into it about 
0.5 c.m. from the bottom. Mercury is placed in the vessel so as to just 
reach to the bottom of the siphon, and electrical contact is made with it 
by fusing a piece of iridium wire into the bottom of the beaker. The 
solution to be electrolysed is placed above the mercury and the spiral anode 
rapidly rotated (500-750 turns per minute). The mercury can be com- 
pletely deposited out in from twenty minutes to half an hour. The 
solution is then siphoned off by pouring in water which causes the 
siphon to act. The pouring in of water is continued until the ammeter 
shows zero. The whole of the waste water is then allowed to flow away 
and is replaced by 90 per cent. alcohol, then by absolute alcohol, and 
finally by two washings of dry ether. The surface is then dried by 
blowing dry air over it for about ten minutes. 
A very considerable amount of work has been done to make the 
 ¥. M. Perkin, Trans. Faraday Society. 
