RECENT PROGRESS IN PHYSICS. 



4o:> 



titles of electricity care found on the condenser at different distances of 

 the plates. 



Distiuice of plates , 



Quantity of induced electri- 

 city ou condenser 



2 lines. 



0.911 



0.887 



0.854. 0.823 



10. 



0. 089 



15. 



20. 50. 



0.612] 0.5001 0.263 



§ 27. Electrical effects of flame. — The electrical properties of 

 flame have been described in. a memoir by Biess, which may be found 

 in Poggendorf's Annalen, vol. LVI, p. 545. In the introduction he 

 gives historical notices of the experiments and views previously pre- 

 sented ou this subject. We will only remark here, that Gilhert^ and 

 Kircher were acquainted with the electrical effect of flame ; Priestly 

 proved experimentally that it was a conductor of electricity, and Volta 

 compared the electrical action of flame to that of metallic points. 



The electrical action of flame may be thus concisely characterized: 

 If an electrified conductor be furnished with a flame, it will at once 

 lose its electricitv, which issues though the flame, as through a point 

 fixed on the conductor; if, on the other hand, a flame be brought into 

 the neighborhood of an electrified body, the flame draws off the 

 electriciV? just as a metallic point does in a far less degree. On 

 placing a flame on the knob of a Leyden jar which is near an electrical 

 machine in operation, the jar charges itself as though the knob had 

 been connected with the conductor of the machine. Volta applied 

 burning sponge to his electroscope, in order to attract atmospheric 

 electricity by this means. 



Although Volta was well aware that flame was a conductor and that 

 it acted like metallic points, and thus had the elements of a correct 

 explanation, yet his views on the action of points themselves were 

 somewhat erroneous, since he believed that the emission as well as 

 the absorption of electricity by points was a consequence of the elec- 

 trical wnnd. In flame the ascending current of air, according to his 

 view, replaced the effect of the electrical wind. 



The electrical wind appears, it is true, when points are strongly 

 charged and favors the emission and absorption of electricity, but 

 the action of points is not dependent upon this wind ; the action takes 

 place even in electrical charges which are too weak to cause the elec- 

 trical wind to appear. 



According to Volta s explanation, an actual communication of elec- 

 tricity takes' place in the electrical action of flame. That the charg- 

 ing and discharging action of points does not always depend on the 

 immediate transfer of electricity is known ; Riess sought to prove this 

 also for flame, experimentally ; he explains the action of flame in the 

 following manner. . . 



A dense current of steam constantly issues from flame, rising as a 

 continuous stratum into the air. But it preserves this form only for 

 a small elevation.* As the air presses on the steam from all sides, 



■= [This passage, which is correctly transcribed from Riess' memoir, is here literallj 

 "translated. That the steam should be decomposed after having been formed by combus- 

 tion, is contrary to what we know of flame, and the author has given no reason for such 

 a -view.] 



