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229 PROFESSOR DAN I ELL ON THE ELECTROLYSIS OF SECONDARY COMPOUNDS. 
of hydrogen H + (S + 4 O) and water (H + O), we may derive an explanation of 
the phenomena much more consistent with the laws of electrolysis which you have 
established than any which has yet presented itself. In this case the current divides 
itself between the two so as to effect the decomposition of three equivalents of water 
and one equivalent of the oxisulphion, and thus four equivalents of hydrogen will be 
evolved at the platinode, and four equivalents of oxygen with one equivalent of sul- 
phuric acid at the zincode. 
The explanation of the alkaline decompositions is no less easy. The solution of 
potassa, for instance, is a mixture of the two electrolytes, oxide of potassium (P + Q) 
and water (H -f- O) : the current divides itself between the two, and electrolyses one 
equivalent of the former, and three equivalents of the latter. Four equivalents of 
oxygen make their appearance at the zincode, one derived from the oxide of potas- 
sium and three from the water; and four equivalents of hydrogen at the platinode, 
one of which is due to the secondary action of the metal upon the water. 
In the second place, let us resume the consideration of the experiment with bisul- 
phate of potassa. We have already seen reason to conclude that the solution of this 
salt acts as a mere mixture of neutral sulphate and sulphuric acid in water; and that 
the current is conducted in a small part by the decomposition of the salt, and still 
more abundantly by the dilute acid. We must now consider the solution as contain- 
ing three electrolytes, namely oxisulphion of potassium P -j- (S -f- 4 O), oxisulphion 
of hydrogen II -f (S + 4 O), and water (II -f- O), and the results of the electrolysis 
agree very well with the supposition that the current divides itself between the three, 
so as to effect the decomposition of one equivalent of oxisulphion of potassium, one 
equivalent of oxisulphion of hydrogen, and two equivalents of water. 
The two following Tables will exhibit the results of the actual experiment, and 
those of an equivalent calculation founded on the hypothesis ; from a comparison of 
which it will appear that, considering the numerous sources of inaccuracy in the ex- 
periments, the agreement is very close : taking, indeed, the different quantities of sul- 
phuric acid as the more certain measure of the effects it is almost perfect. 
Table I. Experimental Results. 
Before the electrolysis the solution contained 
Neutral salt. 
Acid. 
Alkali. 
Free acid. 
104-2 
= 47-3 
+ 57 
44 
Zincode after Electrolysis. 
86-0 
= 39-0 
+ 47 
64 
(-18-2) 
(-8-3) 
(-10) 
(+20) 
Platinode after 
Electrolysis. 
122-0 
= 55 
+ 67 
26 
(-1-18-2) 
(+8*3) 
(+10) 
(-18) 
