186 Description of a Carbon Voltaic Battery. 



then goes on to describe the phenomenon. Dr. Kane also and 

 Prof. Daniel, in their several works, refer to this fact as of recent 

 observation. Now it is not a little remarkable, that at this Jate 

 day this fact should be esteemed either rare or wonderful, since 

 the same phenomena were more than twenty years ago described 

 by Dr. Hare and Prof. Silliman, and have been witnessed ever 

 since by all who have used or seen the powerful deflagrators of 

 Dr. Hare.* Is not the carbon, when thus transferred, in the state 



of vapor? 



It is not my wish in this article, to extol the merits of my bat- 

 tery, at the expense of any other, but merely to call attention to 

 what I believe to be an important modification of Mr. Grove's 

 admirable contrivance. 



Yale College Laboratory, Dec. 14, 1842. 



P. S. Since this article was written, I have, by simple acci- 

 dent, found (while looking for another matter) in the London, 

 Edinburgh and Dublin Philosophical Magazine for January, 1840, 



page 35, a letter to the editors, from Mr. J. T. Cooper, giving no- 



tice of his having employed plumbago and other forms of car- 



bon in voltaic combinations, with highly satisfactory results. 

 This article I had not seen, and it proves again what has been 

 so often proved before, that the same end will often suggest 

 the same means ; but undoubtedly the claim of priority in this 

 case belongs to Mr. Cooper, to whom I cheerfully yield it. I 

 have not, however, heard that any one has taken advantage of 

 Mr. Cooper's suggestions to construct a large battery on this plan. 



Dr. Hare also informs me that a similar plan was original with 

 himself, and that a carbon battery was contrived in Germany 

 more than a year since. 



Prof. S. F. B. Morse, (to whom I cheerfully acknowledge my ob- 

 ligations,) has contrived a battery for moving his electro-magnetic 

 telegraph, which surpasses in constancy any heretofore made. 

 He assures me that he has had it in good working condition with- 

 out interruption seven or eight days. Its peculiarity is in inter- 

 posing between the zinc and platina of Mr. Grove's arrangement 

 a second porous cell, containing strong sulphuric acid, which in- 

 terrupts the mixing of the nitric with the dilute sulphuric acid, 



or vice versa. ^ 



* See a correspondence on this subject in the 5th vol. of this Journal, (1822 ; ) p. 

 108 et seq. 7 between Prof. Silliman and Dr. Hare. 



