144 
MR. DANIELL ON VOLTAIC COMBINATIONS. 
salt was abundantly precipitated by nitrate of baryta and by potassa, the precipitate 
in the latter case being redissolved by an excess of the alkali. It was not in the 
slightest degree affected by nitrate of silver ; proving that no muriate or chloride 
existed in it. There were no indications of free ammonia in the exterior cell : the 
precipitated copper however did not exhibit the beautiful bright pink hue which it 
ordinarily presents, but was of a dull, greyish, earthy appearance, resembling that of 
copper over which ammoniacal gas has been passed at a red heat, and probably con- 
tained some combined nitrogen. I had not, however, time to examine a product 
which is worthy of further investigation. 
I tried one more experiment with a view to complete the inquiry into the probable 
advantage of changing the battery charge. I placed a saturated solution of common 
salt in contact with the zinc, and filled the exterior division of the cells with a satu- 
rated aqueous solution of sulphate of copper. With a temperature of 70° the following 
series of observations was made : 
Time. 
Interval. 
Voltameter. 
5 min. rate. 
h m 
11 11 
/ 
Cubic inches. 
Cubic inches. 
11 15 
4 
3-5 
4-3 
11 19 
8 
5-9 
3* 
11 23 
12 
8-0 
26 
11 2 7 
16 
9-9 
23 
11 31 
20 
11-6 
2T 
11 34 
11 54 
20 
4- 
TO 
A fluid ounce of muriatic acid was added to each interior cell, and the action was only 
brought up to 2’7 cubic inches per five minutes. It thus appeared that the substitu- 
tion of solutions of the muriates for dilute sulphuric acid, was in every way disadvan- 
tageous ; and it was moreover found that when the circuit was broken the copper be- 
came seriously injured by their action and the formation of a submuriate of that metal. 
Wishing now to extend the inquiry into the influence of high temperatures upon 
the voltaic current, and finding that the membranous tubes would not be able to 
resist the action of the acid under these circumstances, I endeavoured to find some 
substitute for the partition of the cells which would not be liable to injury from this 
cause. After several trials I found that porous earthenware, of the same texture as 
that of which wine coolers are commonly made, would answer my purpose suffi- 
ciently ; and the arrangement which I ultimately adopted simplifies the construction 
of the battery to such a degree as to render it advantageous even under circum- 
stances of ordinary temperature. 
The interior cells consist of tubes of this earthenware, closed at the lower end, of 
the diameter of 1^ inches, and of the same height as the copper cells. The bottoms 
of the latter are fitted with sockets, in which the tubes are placed, and which confine 
