PECULIAR SECRETIONS. 373 
in a slip of tinfoil fixed on sealing wax. The animal is 
capable of giving its shocks in the air, as well as in its na- 
tural element the water. Those given in the former are 
even much stronger than in the latter, owing probably to 
the fluid being more confined by the surrounding medium. 
The shock is given with the same degree of force, even 
when the animal is insulated, and the person receiving it 
likewise insulated. In such circumstances, fifty shocks 
have been received in the space of a minute and a half. 
The most powerful effect is produced by these organs, 
when the circuit is made between. their upper and under 
surfaces, as these appear to be in opposite states of electri- 
city. 
The history of animal electricity received some valuable 
additions from the experiments of Dr W1L11aMson in Phi- 
ladelphia *, on the Gymnotus. He found that this animal 
could communicate its shock to the hand, in water, even 
when held at the distance of three feet. It killed small fish 
by the shock, without coming into actual contact, and stun- 
ned larger ones in the same manner. 
In both these fishes, the electrical energy is insufficient to 
produce appearances of attraction and repulsion in the most 
delicate electrometers, although feeble sparks have been 
perceived by different observers, in consequence of using 
the utmost precaution in interrupting the circuit. The ani- 
mal has the power of making the discharge from any part 
of the surface of its peculiar organ, or from the whole, at 
pleasure ; but it is incapable of communicating shocks for 
any length of time, without exhibiting unequivocal symp- 
toms of fatigue. If the electrical energies of the fish are 
too much excited, it becomes debilitated, and expires. 

* Phil, Trans. 1775, p. 94. 
