£o Scientific Niws, /iccounts of Boohy iife. '" ' 



ElcElric Shock by means of Galvanifm. 



IN anfwer to a letter on the fubje£l: of the note at page 44, Mr. Crulckfhank has 

 favoured me with an account of the experiment in which the common elc£lric jar was 

 charged by Galvanifm, fo as to give a perceptible (hock : a faft on the poflibility of which 

 all doubt has, with rcfpe£l to myfelf, been removed by my firft experiments with talc, 

 with filk, and with common air ; a plate of which, over the condenfer of Volta, may be 

 fo charged with Galvanifm, from a weak power, as to exhibit every eleftric intenfity that 

 Bennet's eledtrometer is capable of, merely by varying the thlcknefs of the ftratum of air. 



Mr. Cruicklhank made his experiment as follows : A coated jar, whofe infide and outfide 

 coatings were moiftened, was placed upon one of the extremities of the pile, and a wire 

 connefted with the infide coating, was then made to touch the other extremity. After 

 this procefs the jar was taken in the hand which was wet, and the wire brought to touch 

 the tongue. In this cafe, when the machine was very powerful, and gave ftrong fparks, 

 he was feveral times confident that he received a flight fliock in the tongue, but this did 

 fiot always fucceed, nor could he account for its failure. In truth, the reafoning on thefe 

 fa£ls by application of what we know of the laws of common cleftricity, is fufficiently 

 obvious ; but till we are better acquainted with the laws of eleftric condenfation in the pile, 

 wc muft expedt anomalies tending to embarrafs our procefles of deduftion. I have met 

 with feveral ; of which like Mr. Cruickfliank, in the prefent inftance, I have deferred the 

 publication till time fhould admit of repeating them with fuch variations as the fadls them- 

 fclves have fuggefted. 



From the fame private communication I copy the following curious extract : — " I ftill 

 " ufe the new apparatus or troughs, which was defcribed in your Journal, and have never 

 *' once had occafion to remove the pieces. Indeed, when frefh filled with a folution of 

 *' common fait, to which a little muriatic acid is added, it is quite as powerful as when 

 *' firft conftru£led. I prefer the muriatic acid to the nitrous, as its efFe£ls are much 

 *' more permanent, and it does not in any fenfible degree a<3: on the filver. The (hocks 

 '' given by the troughs are exa£lly fimilai to thofe of common eledricity, and have none 

 *• of that grating or tearing fcnfaiion fo remarkable in thofe from the pile. From two 

 " troughs, containing in all 120 pair of pieces, a fpark of confidcrable fize may be taken, 

 *' and the report or fnap may be heard in an adjoining room. The fpark may likewife 

 *' be taken from water, or from a condu£tor at a diftance, which I never could do with any 

 *' pile. If a point be prefented to the water, a curious hiding is perceived, and a portion 

 ** of the fluid is inflantly converted into gas and vapour : I have fomelimes diflipated a 

 ** whole drop in this way. I have likewife feen a very (Irong fpark run along a plate of 

 ** zinc, to get to water in a manner which I cannot yet explain : this is frequently ac- 

 ** companied with a hifling noife. In fhort, I have obferved a number of curious fads 

 ** with this apparatus, which had efcaped notice, when I employed the piles only." 



