Galvanic Powers of different Metals. 317 



combined in the form of a galvanic apparatus would produce, particularly /tom<j; whe- 

 ther it would a6l with the other metals in a manner fimilar to gold or filvcr, forming always 

 the gafeous bafe of the apparatus ; or whether it would be capable of ading with thofe 

 metals like zinc, iron, &c. and form the oxydating pole of the combinations; hut platina, 

 particularly in a malleable ftate, was found, upon enquiry, to be too cxpenfive an article 

 to be employed by an individual for this purpofe, efpecially at a time, when money is fo 

 frequently required for many other experiments ; indeed it might, in fome degree, be fub- 

 mkted to examination in ifs granular form, by means of the appvaius which I ufed in 

 the experiments with the quickfilver. 



Experiment 6. The obje£l of this experiment, was to examine the cffedts produced by 

 increafing the number of pieces that compofe a galvanic apparatus ; and to afcertain whe- 

 ther its power increafes in a greater proportion, by augmenting the number of metallic 

 plates, or by extending their furface. 



The firft apparatus confided of 200 half crown pieces, combined with 200 pieces of 

 zinc of the fame diameter ; and the difcs were leather foaked in pure water. This appa- 

 ratus was placed upon the board before defcribed, extending in length 3 feet 9 inches. The 

 efFefts of this combination were very feeble in proportion to its dimenfions } when com- 

 pared with an apparatus of forty pair of plates, its power was not increafed in the propor- 

 tion of 5 to I. It was then re-conftrufted, and put together with leathern difcs foaked in 

 a folution of muriate of ammonia {fal ammoniac). 



The refult was, that this apparatus afted very powerfully; the caufticity, and the gal- 

 vanic fhock were more fevere ; the oxidation of the copper wire was more rapid ; and the 

 bubbles of air more copioufly formed in the tubes of water. When the tongue was made 

 part of the circuit, the fenfation, which in the fmaller apparatus feemed to be rather 

 cauftic, refembled in this a pulfation, upon every repetition of the fhock ; when the fhock 

 was received upon the cheek, a flafh of light appeared before the eyes, as when the tongue 

 had formed a part of the circuit. When two wires connefled with the bafes of this appa- 

 ratus, were immerged in feparate veflels of water, and the fingers of each hand were 

 brought into contaft with the water only, a galvanic (hock was very perceptible, and a con- 

 tinued numbnefs was felt, if the fingers were permitted to remain in the water. From 

 this experiment it is obvious, that the increafed effects of a galvanic apparatus, depend 

 more upon the nature of the fubftances which enter into its compofition, than upon the 

 number of metallic plates. 



PART II. EXPERIMENT 6. 



In this experiment, it was propofed to examine the effefts of a galvanic apparatus com- 

 pofed of 20 pairs of metallic plates, each fix inches diameter, but being difappolnted in 

 obtaining the plates of zinc, the experiment has been deferred. The combinatbns of 

 lead, iron, lead, and tin, have been examined, and from the increafed effefts which they 

 exhibited, and which are always very feeble, there is little reafon to expeil,^ that the in- 

 creafed 



