104 DR. FARADAY'S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XII.) 



muriatic acid gas was in the vessel a ; for on charging the small balls s and S posi- 

 tively, all the discharge took place through the air; but on charging them negatively, 

 all the discharge took place through the muriatic acid gas. 



1400. So also, when the conductor n was connected only with the muriatic acid 

 gas apparatus, it was found that the discharge was more facile when the small ball s 

 was negative than when positive ; for in the latter case, much of the electricity passed 

 off as brush discharge through the air from the connecting wirejr?; but in the former 

 case, it all seemed to go through the muriatic acid. 



1401. The consideration, however, of positive and negative discharge across air 

 and other gases will be resumed in the further part of this, or in the next paper. 



1402. Here for the present I must leave this part of the subject, which had for its 

 object only to observe how far gases agreed or differed as to their power of retaining 

 a charge on bodies acting by induction through them. All the results conspire to 

 show that Induction is an action of contiguous molecules (1295. &c.) ; but besides 

 confirming this, the first principle placed for proof in the present inquiry, they greatly 

 assist in developing the specific properties of each gaseous dielectric, at the same time 

 showing that further and extensive experimental investigation is necessary, and 

 holding out the promise of new discovery as the reward of the labour required. 



1403. When we pass from the consideration of dielectrics like the gases to that of 

 bodies having the liquid and solid condition, then our reasonings in the present state 

 of the subject assume much more of the character of mere supposition. Still I do 

 not perceive anything adverse to the theory in the phenomena which such bodies 

 present. If we take three insulating dielectrics, as air, oil of turpentine and shell-lac, 

 and use the same balls or conductors at the same intervals in these three substances, 

 increasing the intensity of the induction until discharge take place, we shall find that 

 it must be raised much higher in the fluid than for the gas, and higher still in the 

 solid than for the fluid. Nor is this inconsistent with the theory ; for with the liquid, 

 though its molecules are free to move almost as easily as those of the gas, there are 

 many more particles introduced into the given interval ; and as respects the latter 

 circumstance, the same is the case when the solid body is employed. Besides that, the 

 cohesive force of the body used will produce some effect ; for though the production 

 of the polarized states in the particle of a solid may not be obstructed, but, on the 

 contrary, may in some cases be even favoured (1164. 1344.) by its solidity or other 

 circumstances, yet solidity may well exert an influence on the point of its final sub- 

 version, (just as it prevents discharge in an electrolyte,) and so enable inductive inten- 

 sity to rise to a much higher degree. 



1404. In the cases of solids and liquids too, bodies may, and most probably do, 

 possess specific differences as to their ability of assuming the polarized state, and 



