4S6 On a Foliate Battery charged V-nte Sulphate of Copper. 



hours. The charcoal points were then again tried ; and if 

 there were any alteration the power of the battery had in- 

 creased. Batteries charged in this manner will continue in un- 

 abated action for upwards of three hours ; in fact until there 

 no longer remains any copper in the solution. It is worthy of 

 notice, that after the batteries have been in action some time, 

 a large portion of the sulphate of copper is expended, and re- 

 placed by sulphate of zinc, yet the action continues the same. 

 This naturally suggests using a saturated solution of any neu- 

 tral salt, common salt for example, and adding merely as much 

 of the solution of copper as will serve for the time required. 

 It is not unlikely that the effect would be more continuous than 

 with a solution of copper only. I intend trying this, as I am 

 still pursuing my inquiries on this subject, the object of which 

 is to simplify as much as possible the voltaic battery. 



At the Marylebone Institution, on Monday, September 12, 

 when a lecture was delivered on this subject by Mr. Hemming, 

 the President, the power used was the hundred pairs of Cruick- 

 shank's arrangement before alluded to, and one hundred and 

 thirty-two pairs of WoUaston's four-inch plates, making in all 

 two hundred and thirty-two pairs. 



The batteries I charged before the commencement of the 

 lecture, and they were not used till an hour afterwards ; the 

 effects were very striking. The arc from the charcoal points 

 passed through a space of three quarters of an inch, and the 

 effect continued unabated for as long a time as could be spared 

 ibr this experiment; soda was rapidly decomposed, and the so- 

 dium brilliantly deffagrated : all the other experiments before 

 cited were repeated on a much grander scale. The lecture 

 being concluded two hours and a quarter after charging the 

 batteries, the charcoal points were again ignited to light up the 

 spacious theatre, the gas having been extinguished. The shock 

 was very powerful, even when taken with the hands dry*. 



Fifty pairs of four-inch plates on Cruickshank's plan suffice 

 for all the above experiments, except the decomposition of the 

 fixed alkalies. 



* [As similar experiments to those here detailed have been performed 

 with batteries of no extraordinary dimensions, charged in the usual way, it 

 would have been more satisfactory had the author informed us of the size 

 and number of the |)lates requisite to produce the same effects when sul- 

 phate of copper was not employed. We refer our readers who are inter- 

 ested in the philosophical investigation of this subject to an admirable 

 Essay by Dr. Marianini of Venice, of which an abridgement will be found in 

 the Aniiales de Chimie et de Physique, vol. xxxiii. p. 113. In his investiga- 

 tion of the various causes which influence the energy of the pile, he has 

 been led to examine the effect of different liquid solutions, and gives a 

 table of the relative advantages of forty-nine acids and salts, one part of 

 each being dissolved in one hundred of distilled water. —Edit.] 



