1835.] Philosophical Transactions for 1834. 307 



Transactions, it was demonstrated that the electricity of the torpedo 

 is capable of acting like voltaic electricity in effecting chemical de- 

 compositions. He enumerates at present all the tests or indications 

 of the electricity of the torpedo now known, which are : 1st, the 

 philosophical effect, as the sensation it imparts is sometimes called : 

 2d, the chemical effects, as the precipitation of iodine, the decompo- 

 sition of water, &c. : 3d, its effect on the thermometer, galvanometer, 

 and on steel in the spiral. These tests are, in point of delicacy, in 

 the order in which they are enumerated. Dr. Davy has been unsuc- 

 cessful in his attempts to elicit a spark from the torpedo, although it 

 has been said that a spark has been obtained from the Gymnotus 

 electricus. 



With regard to the seat of the electrical power, it appears that 

 when the brain has been divided longitudinally, the fish has conti- 

 nued to give shocks. When the brain was completely removed the 

 fish instantly lost this power. Humboldt stated that a shock may be 

 procured by touching only one surface of the fish, but Davy finds 

 that it is necessary to touch the opposite surfaces of the electrical 

 organs, or a conductor or conductors connected with them, before a 

 shock can be received. On some occasions a shock was received when 

 only one surface was apparently touched, but in that case the dis- 

 charge probably took place through the water, and when one surface 

 is touched, the animal instinctively makes an effort to bring the other 

 surface in contact with the offending body. 



There appears, however, to be no connexion between the muscular 

 and electrical power. Two views may be taken of the phenomenon. 

 It may be considered either, 1st, a form or variety of common elec- 

 tricity ; or 2d, a distinct kind ; or 3d, not a single power, but a com- 

 bination of many powers. The first opinion is supported by Dr. 

 Faraday. The only objection to it is the interruption of the torpedinal 

 electricity by the smallest quantity of air, and its want of the power 

 and attraction of the air, which affords some foundation for the 

 second idea. 



The origin of the electricity of the fish may also be urged as an 

 argument for its specific nature, but without much plausibility, 

 because, we are ignorant of its cause and nature. The third opinion 

 may serve as a guide for more minute investigation. The author 

 suggests that other varieties of electricity may owe their effects to 

 the union of several powers, or ethereal fluids, and their peculiarities 

 to the predominance, in various degrees, of these fluids. Dr. Davy 

 found the skin covering the electrical organs, deeper coloured and 

 thicker than below, more vascular, with stronger muscles, and more 

 mucus, the under surface having a greater supply of cutaneous 

 nerves, and a blood-vessel enlarged into a little bulb, situated one 

 on each side of the porta, below the plexus of nerves supplying the 

 the pectoral fin, the use of which may be to propel the blood into the 

 pectoral fin and electrical organ. 



The only remaining paper connected with electricity, in this por- 

 tion of the Transactions, consists of an account of experiments by 

 Mr. Wheatstone, on the velocity and duration of electric light. In 



x2 



