HISTORY OF GALVANISM. 299 



peds. In a fecond letter which is printed in the fame vol. of 

 the Phil. Tranf. Volta purfues his experiments and obferva- 

 tions upon the fubject of galvanifm. If a (ingle mufcle, or a 

 part of it be armed with coatings of two different metals, and 

 thefe be made to communicate by a conductor, the contrac- 

 tions will be excited, but no effect will be produced if two 

 coatings of the fame metal be employed. Worms and fnails Of the various 



he found could not be excited by this influence ; but flies, «»n»ls, thofe 



r », only were fauna 



beetles, grafshoppers, and butterflies, he found were lubject to beaffeaed 



to its action. Upon the whole it appears that thofe animals which have dif- 

 only which have diitinct limbs, with flexor and extenfor muf- and thofe ^ uf- C * 

 cles, are excitable by animal electricity. In thofe animals cles only which 

 which are acted upon by the galvanic influence, Volta found ^ ^^ 

 that it was only the mufcles which are under the direction of 

 the will that can be made to retract ; in his experiments he 

 never perceived that the heart was affected by the two metals, 

 though this organ is thrown into ftrong contractions by the 

 flighted chemical or mechanical ftimulus. The two metals 

 which were found by their union to perform the moil power- 

 ful effects were zinc and filver. Volta placed thefe metals Zinc and filver. 

 one on each furface of the end of the tongue j when they were 

 brought into contact no motion was produced, but a ftrong 

 fenfation of tafte was excited. When the metals were applied 

 to the root of a tongue cut from the mouth, contractions were 

 produced. 



In the fame year in which VoIta\s leiters appeared in the Fowler's Effay, 

 Phil. Tranfactions, Fowler publifhed aneflay on Animal Elec- I7 ?3» Whether 



r J galvanifm be 



tricity ; thefe works muft therefore be confidere as equally ele&ricity. 

 original. The extracts given above from Volta's letters, 

 prove that he confidered the phenomena of galvanifm *-o de- 

 pend upon the operations of the electric fluid; other experi- 

 menters however conceived it impoflible to reconcile the new 

 difcoveries with their previous ideas of the nature of electri- 

 city, and Fowler commences his treatife by this enquiry. In 

 order to afcertain this point he inveftigates the circumftances 

 which are neceffary to the production of the mufcular contrac- 

 tions. Thefe he found to be the contact of the two metals Conditions of 

 with each other, and their communication with the animal ; the e ,.!L : 



' . ' two different 



the contractions may alfo be produced by bringing the metals metals fhould 

 in contact with each other in water, without either of the touch each other 

 metals touching the animal. When the metals are applied to v \ z , t h e nerve' 



the and mufcle j 



