12 
PROFESSOR DANIELL AND DR. MILLER ON THE 
code cell for its reception, and then to determine its quantity and its properties from 
those of the salt which was formed by secondary combination. 
The arrangement which we now made was to place the salt at the zincode with 
the view of passing its bases into an acid at the platinode. We commenced our ex- 
periments with the double sulphates with the view of comparing the different hydrates 
of the sulphuric acid with the hydrates of the phosphoric acid already examined, 
and throwing more light upon the results of the electrolysis of the dilute acid. 
(s.) Some pure sulphate of potassa and copper (CuO, S0 3 , + KO, S0 3 ) was care- 
fully prepared, and its solution placed in the zincode and connecting cells of the 
diaphragm apparatus : the platinode cell was charged with dilute sulphuric acid, the 
current of twenty cells of the battery was transmitted through the arrangement until 
48 cubic inches of hydrogen had been collected from the platinode, and 23*5 cubic 
inches of oxygen from the zincode (about one equivalent in grains), when the process 
was stopped. The platinode solution was perfectly colourless with a very slight de- 
posit of copper upon the platinode, amounting only to 0*1 grain. It was evaporated 
to dryness in vapour of ammonia, and the residue was perfectly white sulphate of 
potassa, which weighed 21 grains. It was entirely soluble in water: and ammonia 
did not produce the slightest blue colour in its solution. The liquids of the zincode 
and connecting tubes together required 51 grains of dry carbonate of soda to neutra- 
lize the free acid. Now, it will be observed, that the sulphate of potassa was only 
one grain less than a quarter of an equivalent, which considering the nature of the 
processes by which these quantities were determined, will appear a very near approxi- 
mation ; and we may take the results of the electrolysis to have been as follows : — 
For one equivalent of force as measured by the gases evolved at the zincode and pla- 
tinode, half an equivalent of oxysulphion of potassium (sulphate of potassa) was de- 
composed (as measured by the quarter equivalent potassium transferred), and half an 
equivalent of oxysulphion of hydrogen (aqueous sulphuric acid) : for it will be ob- 
served, as most remarkable, that the quantity of copper transferred was perfectly in- 
significant. 
Upon the view of the principle of electrolysis hitherto commonly admitted, viz. de- 
finite decomposition with equivalent and opposite transfer of the elements or radicles 
of the compound to the opposite electrodes of the battery, these results were suffi- 
ciently perplexing : but our perplexity increased as we proceeded; and it was not 
till after we had expended an incredible amount of labour in testing different hypo- 
theses of various resistances and opposing forces, supposed to be developed in these 
complicated cases, that we thought of questioning the principles themselves. These 
abortive attempts we shall not, of course, obtrude upon the Society, but proceed 
to select such experimental evidence as may be sufficient to establish, in as concise a 
manner as possible, the conclusions to which we have arrived. 
( t .) A solution of sulphate of alumina and potassa (alum) (Al 2 0 3 , 3SO a ) 4-(K0,S0 3 ) 
