PHILOSOPHICAL TRANSACTIONS 
VIII. Sixth Letter on Voltaic Combinations. Addressed to Michael Faraday, Esq., 
D.C.L. F.R.S., Fullerian Prof. Chem. Royal Institution, fyc. fyc. 8$c. 
By J. Frederic Daniell, Esq., For. Sec. R.S.,Prof. Chem. in King's College, London. 
Received April 22, — Read April 28, 1842. 
My dear Faraday, 
I MUST beg permission to address you once more upon the subject of Voltaic Com- 
binations. To this I am prompted by several considerations. 
In the first place, the beautiful law of Ohm, and the simple expression which he 
has given of the electromotive force and resistances of a voltaic circuit, enable 
me to review with advantage, and to correct, many of the conclusions which I had 
derived from former experiments ; and have suggested additional experiments, the 
results of which will tend, I trust, to remove some obscurities and ambiguities which 
were left in my former communications. 
2nd. By following out these principles I shall be enabled to offer some practical 
remarks upon the different forms of voltaic batteries which have been brought for- 
ward to assist the speculations of the active inquirers, who, in the present day, are 
so eagerly engaged in applying the voltaic forces to the service of the arts. 
3rd. I wish most particularly to explain more fully the principles of the cylindri- 
cal arrangements of the battery which I have introduced, and which appear to me to 
have been greatly misunderstood. 
I am desirous, however, that you should understand that I do not present the fol- 
lowing observations for the purpose of testing the law in question, or of determining 
constants connected with the formula, for that could only be satisfactorily effected by 
experiments of a much more delicate and accurate nature than those to which I shall 
have to refer ; but with a view to show how generally the law applies, even to the practi- 
cal results of operations carried on upon, what might be called, a manufacturing scale, 
in which disturbing influences are numerous, and in a great measure uncontrolable. 
Professor Ohm has adopted (I believe that you will concur with me in thinking, 
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