536 
W. J. TORRANCE. 
and the equilibrium is restored, but chemical action continuing the 
constant current is the result. Such is the galvanic circuit, and 
in the ordinary zinc and carbon batteries we must not forget that 
the current flows from the metal most acted upon—the zinc—thro’ 
the fluid to the carbon and from thence through the connecting 
wires to the zinc. The carbon, therefore, is electro-negative to 
the zinc, and its pole or discharger is the anode or positive pole, 
and the current flows from the positive pole of the carbon to the 
negative pole of the zinc. The property of creating differences of 
potential is called electro-motive force, and is truly an imaginary 
force moving an imaginary fluid. The resistance offered by the 
conducting wires is universely proportional to their sectional area, 
and directly to their length and varies with the specific conduct¬ 
ing power of the metal used. Metallic resistance to a constant cur¬ 
rent is the principle engaged in the production of luminous jets, 
the galvano-cautery, &c. 
Electrical luminosity has been utilized in therapeutics, surgi¬ 
cally upon the larynx and similiar organs in the hands of 
specialists. 
The electrical density of a current refers to the relation 
existing between the area of the substance traversed and the 
quantity of the fluid disengaged. 
The human epidermis, as has been mentioned of the hair of 
the horse, offers a strong resistance to the current; but this may 
be partially overcome in practice by increasing the size of the 
electrodes, the pressure and length of application, and by the 
use of a saline solution upon the surface. For medical purposes 
it is advantageous to connect “ cells ” in “ series,” rather than by 
superficial arrangement. 
Electrolysis is the electrical separation of the elements of a 
compound into its individual electrolytes, none of which can be 
further decomposed. Solution favors electrolysis ; yet it is doubt¬ 
ful whether the tissues of the animal body, semi-fluid as they 
are, exhibit in any degree the electrolytic phenomena of the 
gathering at the anode or positive pole of O. chi., the acids and 
electro-negative elements, or at the catteocle of electro-positive 
elements, such as H, the alkalies and the metals. The elec- 
