160 
MR. DANIELL ON VOLTAIC COMBINATIONS. 
Postscript. 
I have just completed a constant battery of large dimensions, the effects of which 
exceed my most sanguine expectations, and open new views of the possible applica- 
tion of the extraordinary powers of the voltaic current to economical purposes. It 
consists of only ten copper cells 20 inches high, 3^ inches diameter, as in the first 
battery. The interior partitions are formed by merely tying the open ends of the 
oxen’s gullets to the rings of the colanders for supporting the sulphate of copper, and 
which are made deeper than before, and suspending them in the cells, to the bottoms 
of which they reach. These membranous bags contain each rather more than a quart 
of the dilute acid. The zinc rods are of the diameter of -fth of an inch, well amalga- 
mated, and the connections are made as before described. At the temperature of 67° 
this battery produces, in the voltameters which I have all along employed in these 
researches, 12 cubic inches of the mixed gases per minute, or 720 cubic inches per 
hour. Its powers of ignition are very great ; and while it will maintain 6 inches of 
platinum wire -nhrth of an inch diameter red hot, it will still decompose water at the 
rate of 14 cubic inches per five minutes. The permanence of this result is very 
striking. 
When the battery is not in use the rods are taken out and wiped, and the mem- 
branous bags carefully lifted out of the cells, emptied of their acid, filled with water, 
and suspended from a frame placed for their reception. By this treatment I do not 
find that they are liable to any change of texture or deterioration ; and I have now 
membranes which have been in use for several months and are quite perfect. If the 
acid be perfectly washed out of them they may even be dried with impunity; but it 
is better to preserve them in a moist state, as when dry they are liable to crack. The 
acid solution of sulphate of copper remains in the cells without injury, and in ten 
minutes the battery, when required, may be brought into action. There is no reason 
to think that the limits of efficiency have yet been nearly attained, and the gullets 
could easily be connected together so as to obtain bags of any required length. I 
scarcely, however, think that in simplicity and cheapness of construction the battery 
can be further improved. 
Kings College, 
15 th June, 1837- 
J. F. D. 
