Chemical Science. 381 



equal increments. A coated surface, charging in any degree short 

 of saturation, receives equal quantities in equal times, all other things 

 remaining the same. The quantity passing from the outer coating 

 is always proportional to the quantity added to the inner. 



ii. The quantity of matter accumulated may be estimated hy the 

 revolutions of the plate of the electrical machine, supposing it in a 

 state of uniform excitation ; or it may be measured by the explosions 

 of a jar connected with the outer coatings. It is as the surface 

 multiplied by the interval which the accumulation can pass : when 

 the surface is constant, it is as the interval ; when the interval is con- 

 stant, it is as the surface. It is also as the surface multiplied by 

 the square root of the free action or intensity : when the surface is 

 constant, it is therefore as the square root of the attractive force. 



iii. The interval which the accumulation can pass is directly pro- 

 portional to the quantity of matter, and inversely proportional to 

 the surface : it is as the quantity divided by the surface : if the mat- 

 ter and surface be either increased or decreased, in the same propor- 

 tion the interval remains the same. If, as the matter be increased, 

 the surface be decreased, the interval will be as the square of the 

 quantity of matter. 



iv. The force of the electrical attraction varies in the inverse ratio 

 of the square of the distance between the points of contact of the op- 

 posed conductors, supposing the surfaces to be plane and parallel ; 

 or otherwise between two points which fall within the respective 

 hemispheres at a distance equal to one-fifth of the radius, supposing 

 the opposed surfaces to be spherical. 



v. The free action or intensity is in a direct proportion to the 

 square of the quantity of matter, and in an inverse proportion to the 

 square of the surface : it is directly as the effect of an explosion on 

 a metallic wire, all other things remaining the same. If the matter 

 and the surface increase or decrease together, so in the same pro- 

 portion the attractive force remains the same. If, as the matter be 

 increased, the surface be decreased, the attractive force is as the 

 fourth power of the quantity of matter. 



vi. The effect of an electrical explosion on a metallic wire depend* 

 exclusively on the quantity of matter, and is not influenced by the 

 intensity or free action. It is diminished by accumulating the matter 

 on a divided surface : it is as the square of the quantity of matter : 

 it is as the square of the interval which the accumulation can pass : it 

 is directly as the attractive force of the free action, all other things 

 remaining, in each case, the same: it is as the momentum with which 

 the explosion pervades the metal*. 



7. ON THE EMISSION OF LIGHT DURING THE COMPRESSION 

 OF GASES. 



When certain gases have been suddenly compressed, the evolution 



* Page 97. 

 VOL. I. FEB. 1831. 2 C 



