278 M. Wartmann's First Memoir 



37. This explains why the closure of the circuit induced by 

 the aid of a voltaic pile diminishes the brightness of the sparks, 

 without the direction or the intensity of the current of this ap- 

 paratus having the least influence; the pile evidently acts as 

 an imperfect conductor. 



38. When the inductor circuit is closed by a voltameter in 

 which some acidulated water for example is electrolysed, the 

 quantity of gas obtained in the unit of time is independent of 

 the presence or the absence of the metallic bundles \^faisceaux\ 

 in the bobbin ; it does not vary equally when we pass or arrest 

 a continued current in any direction through the induced 

 wire. 



§ V. Influence of the Atmospheric Pressure upon Induction, 



A. Static Induction or Influence. 



39. Mr. Faraday, in his beautiful researches in electricity, 

 has entered upon the question of the relation which exists be- 

 tween the atmospheric pressure and statical induction*. I shall 

 relate a few of my numerous experiments upon the same sub- 

 ject; experiments which are only new or varied forms of those 

 of the learned English natural philosopher, and which lead to 

 similar conclusions. 



40. I have employed a large electrical machine, the plate of 

 which is 0"^*85 in diameter, and the brass conductors of which 

 are each 0'^"90 long and 0"^*108 in diameter. Under favour- 

 able circumstances it gives sparks 0™*27 to 0'^"32 ; sparks are 

 drawn from it easily at 0°^'l 1 to O'^'IG distance. 



41. On operating in the dark, every time a spark is drawn 

 from the machine, there springs a purple glow {purpurine) be- 

 tween the two balls or the two charcoal points, which termi- 

 nate at an inch distance, the stems of an electrical egg void of 

 air; but this light disappears in proportion to the return of 

 the fluid. With my machine this luminous appearance t 

 scarcely takes place but at a maximum distance of a metre 

 from the conductors, and appears the more brilliant in pro- 

 portion to the proximity of the egg. For each distance it re- 

 mains the same, whether the egg rests upon an insulating 

 support, or whether it is connected with the ground by the 

 mediation of the hand or a metallic chain. 



42. It is not even necessary to draw a spark from the con-^ 



* Experimental Researches, §§ 1613 to 1616; also §§ 1359, 1405, 1626 

 to 1543. 



-(• It is what Mr. Faraday calls glow, and what the Germans designate by 

 das elektrische Glimmcn. It is distinct from the spark, properly so called, 

 spark, brushy funke. 



