ATMOSPHERIC ELECTRICITY. 299 



In his experiments Volta made use of the conductor with which 

 De Saussure had armed his electrometer, but he placed at tlie end of 

 the point an ignited body, such as a piece of spunk or of cotton wick 

 prei)ared with sulphur. By this means he obtained results which 

 were frequently twice as great as those afforded by the apparatus 

 without the use of the ignited body. As to the mode of applying the 

 combustible to the end of the conductor, in order that it might be 

 kept there the necessary time, and not be extinguished by the wind, 

 Volta placed it in the inside of a coil of iron, adjusted to the point of 

 the conductor. He advises also to attach to the same point a little 

 lantern containing a spirit lamp, in case the rain is such as not to 

 allow using simply spunk or tinder or burning sulphur.* 



The great divergence which an electrometer presents when the stem 

 is furnished with an ignited body is worthy of observation. M. Pfafff 

 says that, in the case where he observed no electrical sign with an elec- 

 trometer of gold leaf exposed to the air, even while using a condenser, 

 the leaves diverged more than an inch as soon as he fitted to the point 

 of the stem a piece of ignited tinder. Let there be placed on an ordi- 

 nary electroscope a very small spirit lamp, and at five or six feet above 

 it present a stick of resin feebly electrified ; instantaneously there will be 

 seen, according to M. Pouillet,! a very great divergence of the leaves ; 

 and yet the same body with the same electrical charge produces no 

 sign of divergence if it be presented to the electroscope without flame, 

 even at the distance of an inch. It might be objected that the elec- 

 tricity which is observed in Volta's electrometer furnished with an 

 ignited body is not the result of the influence of atmospheric elec- 

 tricity, but that it is produced by the action of the flame or smoke on the 

 point of the conductor. This objection appears well founded, since 

 M. Becquerel,§ in causing flame to act on metallic bodies which com- 

 municate with a condenser, observed a disengagement of electricity, 

 the cause of which he attributed to an electro-motive action which 

 existed between the flames and these bodies. To be able to judge 

 how far confidence could be placed in observations made in this 

 manner, Bchiibler || rejicated the same experiments in the open air 

 and in closed rooms. During the burning in the house of three 

 grains of tinder or of sulphur, he could not obtain the slightest sign 

 of electricity with Volta's electrometer ; while the same quantity of 

 these substances burned in the open air, at the same hours in the after- 

 noon, when atmospheric electricity is at its minimum, was suificient 

 to charge the electrometer, or even a small Leydcn phial, to such a 

 degree that it could be used for other researches in electricity. He 

 could scarcely obtain any signs of electricity by the combustion of a 

 hundred grains of spunk or tinder in closed rooms. It follows, there- 



^ M. Matte nci, resting on the electric conductibility of the vapor of phosphorus, prepared 

 in metallic tubes sticks of tliis substance one or two niillimetr(!3 in diameter, to adapt them 

 tben to the point of the conductor destined to receive the atmospheric electricity. — (See 

 liiblioth. Univ. Sc. et Arts, tom. LI, p. .■J5I ; Geneve, 1832.) 



•f Diction, de Gehler, tom. VI, p. 51<S. 



X Ann. de Chim. et de Phys., torn. XXXV, p. 401, 1827. 



§ Ann. de Chim. et de Phys., tom. XXVII, p. 17, 1824:. 



11 Journal de Schweiggor, tom. XIX, p. 1, 1817. 



