122 
MR. DANIELL ON VOLTAIC COMBINATIONS. 
showing the quantity of zinc equivalent to 188 cubic inches of the mixed gases to be 
86- 1 grains ; differing from the quantity actually consumed in each cell only 7*2 grains, 
or 2"3 for each equivalent. The waste of metal, indeed, must have been even smaller 
than this ; for at the bottom of the cells I found a small quantity of amalgam, which 
had fallen off the rods, and which, at the time, it was not convenient to collect, but 
which, if added to the weight, would have materially diminished the deficiency. 
For this quantity of zinc, 166’5 grains of metallic copper must have been precipi- 
tated on each copper cylinder ; for not a bubble of hydrogen made its appearance 
upon them, and 6623 grains of crystallized sulphate of copper must have been con- 
sumed in the Avhole battery, or only 3 77 grains short of a pound avoirdupois. 
Upon examining the cells after the course of experiments, the fresh-precipitated 
copper had a most beautiful appearance, being of a bright pink colour. It was not 
only deposited upon the sides and bottom of the cylinders, but upon the under surface 
also of the colanders. In the angle formed by the junction of the bottoms with the 
sides and at the contact of the membrane with the collars of the cullenders, it was 
collected in the largest quantities, and had a very distinct mammillated structure. At 
these points it is probable that the diffusion of the hydrogen had been impeded, and 
it had consequently accumulated in greatest abundance. 
The charge of sulphate of copper has been left for weeks together in the battery, 
only taking care to keep the bottom of the colanders covered with the solid salt ; but 
the acidulated water was withdrawn from the interior tubes every morning by means 
of a siphon, and a fresh charge substituted. It was generally found very slightly 
tinged with the sulphate, which would have been injurious to the zinc rods. 
The only disadvantage that I am aware of in this new construction of the battery, 
is the unavoidable distance of the generating from the conducting metal, which is five 
or six times greater than in the double Wollaston plates ; and this I sought to ob- 
viate as much as possible by improving the conducting power of the interposed elec- 
trolyte. I made trial of sulphuric acid of four times the standard strength, or 9 
volumes of oil of vitriol to 100 of water, sp. gr. 1105‘4 ; and this I worked for six 
hours continuously, and found the result very steady ; 50 cubic inches with the large 
voltameter, and 5 5 by the smaller, per five minutes of time. 
Taking into consideration the great precipitation of the sulphate of copper, I am 
doubtful whether the solution could be kept in a state of saturation at much beyond 
this rate of work ; and in cases where it may be desirable to maintain a constant 
action for a great length of time, it may not be desirable to carry it even so far; but 
this, with many other questions, I must leave for future examination. 
Being now desirous to bring the constant battery into more immediate comparison 
with one of the usual construction, I took a trough with ten Wollaston plates four 
inches square, which had been but little used, and carefully cleaned and fitted a 
double case of copper to the last zinc, to make the series complete. I charged it with 
a mixture in the proportions of 100 water, 2j oil of vitriol, and 2 nitric acid, and 
