170 On Galvanism. 



employing fewer lotions, infusions, &c., T should obtain » 

 less quantity of salt, but that, as this would change nothing 

 in the nature of the product, I should find it more advan- 

 tageous. 



Having in the first place proceeded to an analvsis, and 

 wishing that as little of ihe salt as possible should escape 

 mc, I conducted the process in a rigorous manner; and 

 since that time I have practised the same manipulation. 



There is reason, however, to think that the operation 

 might be much shortened by the help of alcohol : as this 

 fluid has no action on the calcareous salt of cinchona, it 

 might be employed two ways to remove the resin, which 

 forms the greatest obstacle to the extraction of this saline 

 substance, either bv subjecting the cinchona in its natural 

 state to the alcohol before proceeding to aqueous infusion, 

 or bv exposing to its action the extractive matter which 

 results from the concentration of the first infusions. 



XXX. On Galvanism. By a Correspondent. 

 To Mr. Tilloch. 



N 



SIU, 



S OT having seen or heard any satisfactory' hypothesis coTi- 

 cerning the increased effect produced by the Galvanic bat- 

 tery upon animals by increasing the number of plates, and 

 upon metals by enlarging their surface, 1 beg, through your 

 valuable miscellany, to call the attention of Mr. Daw and 

 other philosophers to the subject ; and shall be happv to re- 

 ceive, through the same channel, an explanation of these 

 apparently inconsistent phienomena. 



It is well known that the eftect on animal bodies is pro- 

 portionate to the series or number of plates of which the 

 battery is composed, and that on metals it increases with 

 the area or surface of the plates employed. The fact is at- 

 tempted to be accounted for upon the supposition that the 

 skin, from being an imperfect conductor, is capable of 

 transmitting only a certain portion of Galvanic fluid, and 

 that metals, being perfect conductors, can transmit anv in- 

 definitely larger quantity. Eut this theory, although it mav 

 be supported by experiment when ecpial nu.mlers of small 

 and large plates are emplnyed, decs not appear to me to 

 account for the phsenoniena when different numbers of 

 plates of equal sizes are used. 



I conceive 



