Curiosities of Science. 05 



points in immediate contact with the wires of your battery ; 

 bring the points together, and they will begin to burn with a 

 dazzling white light. The charcoal points of the large appara- 

 tus belonging to the Royal Institution became incandescent at 

 a distance of ^th of an inch ; when the distance was gradually 

 increased till they were four inches asunder, they continued to 

 burn with great intensity, and a permanent stream of light 

 played between them. Professor Bunsen obtained a similar 

 flame from a battery of four pairs of plates, its carbon surface 

 containing 29 feet. The heat of this flame is so intense, that 

 stout platinum wire, sapphire, quartz, talc, and lime are re- 

 duced by it to the liquid form. It is worthy of remark, that no 

 combustion, properly so called, takes place in the charcoal it- 

 self, which sustains only an extremely minute loss in its weight 

 and becomes rather denser at the points. The phenomenon is 

 attended with a still more vivid brightness if the charcoal points 

 are placed in a vacuum, or in any of those gases which are not 

 supporters of combustion. Instead of two charcoal points, one 

 only need be used if the following arrangement is adopted : lay 

 the piece of charcoal on some quicksilver that is connected with 

 one pole of the battery, and complete the circuit from the other 

 pole by means of a strip of platinum. When Professor Peschel 

 used a piece of well-burnt coke in the manner just described, 

 he obtained a light which was almost intolerable to the eyes. 



VOLTAIC ELECTRICITY. 



On January 31, 1793, Volta announced to the Royal Society 

 his discovery of the development of electricity in metallic bodies. 

 Galvani had given the name of Animal Electricity to the power 

 which caused spontaneous convulsions in the limbs of frogs 

 when the divided nerves were connected by a metallic wire. 

 Volta, however, saw the true cause of the phenomena described 

 by Galvani. Observing that the effects were far greater when 

 the connecting medium consisted of two different kinds of 

 metal, he inferred that the principle of excitation existed in 

 the metals, and not in the nerves of the animal ; and he as- 

 sumed that the exciting fluid was ordinary electricity, produced 

 by the contact of the two metals ; the convulsions of the frog 

 consequently arose from the electricity thus developed passing 

 along its nerves and muscles. 



In 1800 Volta invented what is now called the Voltaic 

 Pile, or compound Galvanic circle. 



The term Animal Electricity (says Dr. Whewell) has been superseded 

 by others, of which Galvanism is the most familiar; but I think that 

 V olta's office in this discovery is of a much higher and more philosophi- 

 cal kind than that of Galvani ; and it would on this account be more fit- 

 ting to employ the term Voltaic Electricity, which, indeed, is very com- 



