CONTACT ELECTRICITY. 11 



apparatus of contact has the same physiological properties, what- 

 ever may be the nature of the elements composing it.^ 



The ajDparatus can be constructed so as to furnish electricity in 

 greater quantity, or of higher tension, according to the effects that 

 it is desired to obtain ; but whatever is done, the different effects 

 are produced simultaneously, and cannot be completely isolated 

 from one another. 



The intermittent galvanic current exerts a triple physiological 

 action at each intermission : one at the moment of completing the 

 current, a second at the moment of breaking it, a third during 

 the interval between these acts. The physiological action produced 

 at the instant of interrupting the circuit is weaker than that at the 

 instant of completing it. Tims, with a pile of thirty pairs of Bun- 

 sen's elements, muscular contraction is not produced, in the human 

 subject, by interrupting the current ; even when moist rheophores 

 are applied over a portion of skin corresponding to the surface of a 

 muscle : but by the same procedure, the electro-physiological effect 

 is very manifest at the completion of the current. The power of 

 the interruption increases, however, in proportion to the number 

 of elements in the battery. It appears to me that a Bunsen's 

 pile of 120 pairs produces at the moment of interruption a con- 

 traction about equal to that produced by a pile of twenty pairs 

 at the moment of completion. 



The physiological action produced in the period between the 

 completion and the interruption of the current is more manifest 

 the longer this period is prolonged. The current passing during the 

 period is called continuous. 



Galvanic electricity can be applied either by continuous or by 

 interrupted currents. 



The continuous current, limited to the skin, excites, besides the 

 phenomena of sensibility above described, an organic effect more 

 or less considerable, from a simple erythema to the production of 

 an eschar. This organic effect, due to the calorific and electro- 

 lytic action of galvanism, is produced but gradually ; at least if the 

 battery employed be not very powerful. 



A constant and very intense continuous current, traversing a 

 limb longitudinally, appears only to produce fibrillar and oscillatory 

 or irregular contractions ; — provided that the current was feeble at 

 the moment of its completion, and was then rapidly raised to its 

 maximum. Such, at least, was the result of a trial made upon my- 

 self with a pile of 120 pairs of Bunsen's elements. The continuous 



* The quantity of electricity furnished I surface of the elements. The tension ia 

 l>y a pile is in direct proportion to the | in proportion to their number. 



