MR. DANIELL ON VOLTAIC COMBINATIONS. 
r27 
it to be. The length of the zinc rods exposed to the action of the fresh acid, which 
must have floated upon the saline solution in this experiment, could not much have 
exceeded one inch, and yet they proved perfectly efficient. I immediately confirmed 
this conclusion by shortening the zinc rods to one fourth of their original length, and 
found no diminution of the power of the battery when charged with fresh acid. 
I next charged the battery with acid of the same strength as that which I employed 
in the voltameters, viz., eight parts of water to one part of oil of vitriol by measure 
(specific gravity 1136), and obtained at once a steady action of IT cubic inches per 
five minutes ; this was therefore the mixture which I employed in all my subsequent 
experiments. 
This rate of action must obviously require some attention to the state of the solu- 
tions in the battery, when perfect steadiness is required to be maintained for a long 
period ; as nearly 25 grains of oxide of zinc are formed, and 154 grains of sulphate 
of copper decomposed in each cell per hour. Nevertheless it will remain constant 
for an hour and a half even without any change of acid ; and the addition every now 
and then of one fluid ounce of fresh acid will maintain the action for any desired 
time, provided the colanders be kept well supplied with the salt of copper. 
Considering the great advantage which had been derived from the extension of the 
surface of the conducting metal of the battery, I now wished to ascertain whether 
this might be carried further ; and for this purpose I caused some cells to be fitted 
up in the interior with ten small plates, one inch wide, extending from the bottom 
to the colander, and converging from the interior circumference towards the centre. 
In this way they just reached to the membranous tube, and the surface of the copper 
was more than trebled. I thought it possible that advantage might be thus derived, 
not only from the great extension of surface, but from the approximation of a part of 
the conducting plate to the generating rod. 
My first experiment was made with five plain cells and five ribbed, working into 
separate voltameters, and I found the products equal, inclining, if anything, in 
favour of the former. The amount of gases from each was, however, only 5’5 cubic 
inches per five minutes, or one half of that from the whole series of ten cells. When 
the ribbed and the plain cells were connected together in one series, the amount in 
one meter was, as before, 1 1 cubic inches. 
It now seemed evident that a series of five did not confer intensity enough upon 
the current to enable its whole quantity to overcome the resistance of the conducting 
fluid between the two metals at the existing distance ; and this being the case with 
the plain cells, no increase of quantity could be expected to manifest itself from those 
with extended surfaces. When the latter were joined with the former, the smaller 
surface of course governed the whole series according to the established law. I there- 
fore completed the number of the ribbed cells to ten, and setting them to work 
against an equal number of plain, the product of the latter was, as before, 1 r cubic 
inches, but that of the former did not exceed 8"5. I have not yet been able to satisfy 
