S-0^ Oh t1:e liLJc^ricity excited fy iLe' 



«ondua;ors, the eleclric current which it excites be able tiS- 

 pafs every where with perfedt freedom. 



I muft often recur to, and- infift on, this laft condition^ 

 feecaufe it is elTential in- all cxperiiiients- when you wifli ta 

 obtain fenfiblc eflcfts on the botlv, or commotions in the- 

 limbs, or fenkitiond ii> the organs of the fenfes. It is necef- 

 fary, therefore, that the non-metallic conductors which entet^ 

 pnto the circle fliould be as good' conductors as poflible, welt 

 moiftened (if they are not themfelves licjuid) with water, or 

 with finy other liquid that may be a better conductor than 

 pure water; and it is neccfliry, befidcs, that the well moift- 

 ened furfaces, by which they communicate with the metallic 

 conduftor, flionld befufficiently large. The communication- 

 ought to be confined or reduced to a finall' number of points 

 of contact only in that place where you wifli to concentrate 

 fhe eleAric aftion on- one of the moft fenfible partsof the 

 body, on any of the fenfilive nerves, &c. as I have alteady 

 remarked in fpcaking of the experiments on feeling, viz, 

 thofc by which acute pains are excited in difTcrent parts. 

 The bed method which I have found for producing on tiitj 

 tongue all the fenfations above defcribed, is, to apply the tip- 

 of it to the pointed extremity (which, however, muft not bo 

 too much' fo) of a metallic rod^ which I make to commu- 

 nicate properly, a& in the other experiments, with one of the 

 extremities of my apparatus, and to cftabllfh a good commu- 

 nication between the hand, or, what vs better, both the hands- 

 together,- and the other extremity. This applitration of the 

 tip of the torrgue to the end of the metallic rod, may either 

 cxift already, when you are going to make the other commu- 

 nication- to complete the circle (when you are going to'im- 

 merfe your har?d into the water of the bafon), or be made 

 aftef the eftablifhmcnt of this communicatron, while the hand 

 is hmmerfed; and in the latter cafe I think I feel the {Kick- 

 ing awd fhbck in the tongue, a very filort time before a6tuaf 

 contaft. Yes '^ it always appears to me, particularly if I ad- 

 vance the tip of my tongne gradually, that, when it has ar- 

 yivtd UTtliin a very fnuall diftance of the metal, the eleftric 

 Suid (l v/ould ahuotl; fay fpark), overcoming this interval^ 

 ia-vts forwards to llrike itr 



