STATIC ELECTRICITY. 5 



This electro-physiological theory has certainly not been founded 

 upon experiment ; for a healthy person, subjected to an electric 

 bath, either positive or negative, does not exhibit any symptoms of 

 an influence either excitant or hyposthenic. 



B. — Sjparhs, and the Leyden Ja?-. 



Whatever may be the forin of exciter that is brought into con- 

 nection with the conductor of an electric machine, and whatever 

 may be the distance that separates this exciter from the skin, the 

 electricity furnished by the machine in action will reunite with 

 that of the body at the epidermic surface, with a greater or less 

 degree of tension. A pointed exciter allows the electricity to escape 

 easily; with a knob the tension is greater and the sparks are 

 less frequent ; but each of these forms discharges itself by a single 

 spark. An exciter having a plane surface discharges itself by 

 several sparks at once (from two to five), if it be at a little distance 

 from the skin. 



A metallic brush acts, in this respect, like a plane surface : 

 that is, it gives off only two or three sparks at a time, whatever 

 the number of threads of which it is composed.^ 



Static electricity applied by the exciter — of which the several 

 actions have just been described — produces always the same sensa- 

 tions, differing only in their degree. These sensations may be 

 compared to those produced by the impact of a small substance 

 striking upon the skin. They are always disagreeable, however 

 weak the electric tension. The feeling is never very acute, nor 

 like that of a burn, or a puncture, whatever form of exciter may 

 be employed. After a time the skin reddens and becomes more 

 sensitive. To render the discharge more painful, it is necessary 

 to employ a degree of tension that can only be obtained by a 

 Leyden jar of modei'ate size, sufficiently charged ; but then the 

 excitation will be no longer limited to the skin, and will produce 

 the effects to be described hereafter. 



Under weak tension, the action of static electricity can always 



' A brush of badger's hair has been determine a current of air to the surface 

 used as an exciter ; and this, being in of the brush. It is this current, analogous 

 connection with an electric machine, and to that which is formed at the surface of 

 being hekl at a short distance from the the plate of an electric machine in move- 

 skin, occasions a sensation of coolness meut, which causes the sensation of cool- 

 and a very slight pricking. Such a ness produced by tlie vicinity of the 

 brush, itself a bad conductor, is charged electritied brush of badger's hair. It is 

 with positive electricity, the excess of j evident that this method of electrization 

 which escapes from the extremities of the [ is illusor}' ; since the natural electricity 

 hairs, to unite with the electricity of j of the body rmdergoes no appreciable in- 

 the surrounding air. The effect is a series fluence. 

 of rai)id and successive re-unions wliicli 



