344 Mvl^em^^ Experiments on the Ekctro-Magnetic ' 



3. Experiments on the Electro-Magnctic properties of . Carbon rvhen> 

 ' in a state of Combustion. 



The following experiments are intended to shew that carbon,, 

 when undergoing combustion, possesses the power of conduct- 

 ing the galvanic fluid of a single pair of plates, in the same man- 

 ner as a continuous metallic wire,— of affecting the needle, — 

 transmitting the metallic taste, and becoming magnetic. 



I shall first describe the apparatus. which I used, as it is sim- 

 ple, and well calculated for conducting electro-magnetic experi- 

 ments. The general principles on which its action depends, I 

 have explained in the last number of this Journal. 



The present construction of the apparatus consists of a circu- 

 lar wooden box, A B, Plate V. fig. 1., four inches in diameter and 

 one deep. From the opposite sides of the box, project two small 

 glass-tubes C D, forming two cup-like cavities on the outside 

 of it ; only one of them C, opening into, and having a commu- 

 nication with, the inside of the box. About half an inch from 

 the bottom, the diameter is lessened nearly a quarter of an inch, 

 so as to form a projecting check round the inside of it, as seen 

 in the plan of it, fig. 2. On this projecting check rests a circu- 

 lar plate of copper, perforated with holes, and having a wire of 

 the same metal soldered to it. 



In order to generate galvanism by this apparatus, a quantity 

 of the liquid amalgam of zinc and mercury is to be poured into 

 it, as much merely as to cover the bottom, and rise into the small 

 tube, which communicates with the inside of the box. The cop- 

 per-plate is then to be placed on the check, and over the whole 

 is to be poured as much of a solution of muriatic acid and water, 

 as will fill the space between the amalgam and the copper-plate, 

 and rise a little above it. The extremity of the wire which is 

 soldered to the copper-plate, is made to dip into the tube D, 

 which has no communication with the inside of the box, and in- 

 to which is also poured a small portion of mercury. 



The apparatus being thus prepared, a communication is 

 formed by wires passing from the two cup-like tubes. The one of 

 these cups C, communicating with the amalgam, constitutes the 

 positive plate ; and the other D^ being in connection with the 



