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XI. Additional Observations on Voltaic Combinations. In a Letter addressed to 
Michael Faraday, D.C.L. F.R.S., Fallerian Prof. Chem. Royal Institution, 
Corr. Memb. Royal Sf Imp. Acadd. of Science, Paris, Petersburgh, 8$c. By 
J. Frederic Daniell, F.R.S., Prof. Chem. in King's College, London. 
Received April 14, — Read April 21, 1836. 
My dear Faraday, 
The Council of the Royal Society having done ine the honour to order the publi- 
cation of my observations upon “ Voltaic Combinations” in the Philosophical Trans- 
actions, I should wish to add the results of some further researches, which may 
render the account of the constant voltaic battery more complete and practically 
useful. 
My great object in this combination was to obtain an invariable current of force 
sufficient to effect chemical decompositions, after overcoming the resistance necessary 
to register its quantity by the voltameter ; and having succeeded in this, it seemed 
to me almost a matter of indifference to the solution of the various important ques- 
tions to which it might be applied, whether the quantity were large or small. I 
quickly, however, discovered that the battery might be rendered not only perfectly 
steady in action but very powerful; and that it would be extremely efficient and con- 
venient for all the purposes to which the common voltaic battery is usually applied. 
I set myself therefore to perfect its construction with this view. 
Before I state the results I wish to direct your attention to some observations which 
affect the construction and application of your voltameter, being convinced that 
anything which may tend to facilitate the use or establish the correctness of that 
most important instrument will prove of substantial benefit to electro-chemical 
science. In my previous communication (p. 112) I stated that I had found that the 
plates of a voltameter only six eighths of an inch wide evolved the same amount of 
gases as two platinum plates one inch wide, and of the same height, in one of the 
cells of the dissected battery, when the former was substituted in the circuit for the 
latter ; and I imagined that “ their nearer approximation had counterbalanced their 
deficiency of surface.” The results of the experiments recorded in the Table (p. 121), 
also show that there was no difference in the indications of the same small meter and 
those of a larger, the plates of which were three inches by one inch when they were 
alternately used. The plates of the larger instrument were moveable, and admitted 
of adjustment to different distances from each other ; and by these means I ascer- 
