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X. Further Observations on Voltaic Combinations. In a Letter addressed to Michael 
Faraday, Esq. D.C.L. F.R.S., Fullerian Prof. Chem. Royal Institution, Corr. 
Mernb. Royal 8$ Imp. Acadd. of Sciences, Paris, Petersburgh, 8$c. By J. Fre- 
deric Daniell, F.R.S., Prof. Chem. in King’s College, London, 8$c. 
Received March 30, — Read April 6, 1837. 
My dear Faraday, 
I HAD intended, ere this, to have addressed you upon the subject of the measure of 
affinity which the constant battery may be made to supply, as indicated by the con- 
cluding' experiment of my last letter ; but my attention has been diverted, and the 
whole of my leisure occupied by what I found to be a necessary preliminary investi- 
gation of the effects of changes of temperature upon the voltaic action. In the course 
of my experiments upon this principal subject, I have also been led to observe some 
curious disturbances and diversions of the battery current, from secondary combina- 
tions ; and I now submit the results of the whole inquiry to your judgment, not with- 
out a hope that you may consider them of sufficient interest and importance to be 
communicated to the Royal Society. 
You may perhaps recollect that the standard charge, which I finally adopted in 
the use of the constant battery, was a mixture of eight parts of water with one of oil 
of vitriol on the side of the zinc, and a saturated solution of sulphate of copper in 
contact with the copper ; and that the average amount of its work, as measured by 
the voltameter, was 1 1 cubic inches of mixed gases per five minutes. It occurred to 
me that the resistance to the current might again be reduced by dissolving the salt 
in the standard acid instead of water ; and upon making the experiment I found the 
action increased from 11 cubic inches to 13 cubic inches, at which rate it steadily 
maintained itself ; the following being the result of one series of observations. 
Time. 
Interval. 
Voltameter. 
h m 
11 0 
✓ 
Cubic inches. 
11 5 
5 
13 
11 10 
5 
26 
11 15 
5 
39 
11 20 
5 
52 
Upon one occasion I prepared the charge by adding one part of oil of vitriol to 
eight parts of the saturated solution of the sulphate, and poured it into the cells 
