ELECTROLYSIS OF SECONDARY COMPOUNDS. 
11 
tassium (K, Cy) in the platinode cell, and a solution of potassa in the zincode and 
connecting - cells. The arrangement conducted well ; gas was given off from both 
electrodes, and cyanide of potassium formed in abundance in the zincode cell. Hy- 
drogen must therefore have been given off at the platinode by the oxidation of the 
potassium evolved, and oxygen at the zincode by the deoxidation of potassa under 
the influence of the current in the formation of the cyanide of potassium. 
(q.) The apparatus was charged throughout with solution of cyanide of potassium, 
and subjected to the current. Gas was given off as before at the platinode ; but at 
first none from the zincode. The liquid in the zincode cell gradually became of a 
deep brown colour, and the electrode itself was coated with a deep brown matter, 
which was easily washed off. In the latter part of the operation gas was also evolved 
in small quantity at the zincode. The solution smelled strongly of hydrocyanic 
acid, of which, by the proper tests, it was found to contain a considerable quantity. 
There can be no doubt that the brown matter which was abundantly formed was para- 
cyanogen, which is soluble in the alkaline solution of the cyanide of potassium, and 
which must have been produced either by the spontaneous decomposition of the 
hydrocyanic acid, or in a way something analogous to the formation of the red ferro- 
cyanide of potassium from the yellow by the absorption of an additional quantity of 
ferrocyanogen. 
(r.) A diaphragm apparatus was charged throughout with sulphocyanide of po- 
tassium (K, S 2 Cy). Upon the first application of the current the action was brisk, 
but soon declined, and when 5^ cubic inches of gas had been collected from the pla- 
tinode and 1^ cubic inch from the zincode it ceased. There was a copious orange- 
coloured deposit in the zincode cell and upon the plate which interrupted the pro- 
gress of the electrolysis ; no particular odour was perceptible in either of the cells. 
The liquid filtered from the zincode became turbid by exposure to the air, and de- 
posited more of the yellow compound. The clear liquid was again subjected to the 
current, which it transmitted readily, and with the same phenomena as before. 
There could be little doubt that sulphocyanogen was the anion transferred in this 
experiment. This part of our subject still presents a tempting field for investigation, 
from which however we were for a time diverted by an important class of facts which 
next fell under our observation ; we have however since returned to the study, and 
are at present engaged in researches upon the cobaltocyanides, and other double 
cyanides, the results of which we hope ere long to lay before the Society. 
6. We were purposing to follow up the examination of the double salts by the 
electrolysis of other classes of these compounds, when we were stopped by the occur- 
rence of a new order of phenomena, which it was necessary to turn aside and examine 
as affecting the very foundation of the process which we were employing. In our 
examination of the phosphates, our plan had been to transfer by electrolysis the acid 
of the salt placed in the platinode cell into a solution of potassa placed in the zin- 
c 2 
