1818.] Mr. Ellis on a Lamp without Flame. 437 



Article IX. 

 On a Lamp without Flame. By Francis Ellis, Esq. 



(To the Editors of tke Annals of Philosophy.) 

 GENTLEMEN, Lansdotcn Crescent, Bath, May 11, 1818. 



An experiment of Sir Humphry Davy's, in his Researches 

 on the Combustion of Gaseous Mixtures, led me, last summer, 

 to the simple mode of keeping a coil of platina wire once heated, 

 in a state of ignition for an indefinite time, without further 

 application of heat, which has been noticed in your Annals by 

 the appellations of the lamp ivithout Jlame, and the aphlogistic 

 lamp. Subsequently it appeared to me probable that if this 

 lamp were put into imperfect communication with the atmosphere, 

 the accumulation of azote, carbonic acid, and other non-inflam- 

 mable elastic fluids, might be so regulated as to reduce the 

 temperature of the wire below ignition without interrupting the 

 slow combustion of the alcohol, or the consequent new combi- 

 nations. With this view, putting the ignited lamp into a hair- 

 sieve of a few inches' diameter, and covering it with a glass 

 funnel nearly closed at top, of rather smaller diameter than the 

 sieve on which it rested, the wire soon became apparently 

 extinct, and afterwards grew black. The continued deposition 

 of moisture on the interior of the funnel showed, however, that 

 the decomposition of the alcohol had not ceased ; and when, 

 after some hours, the funnel was removed, the lamp re-ignited 

 with a distinctly perceptible crackling, caused by the inflamma- 

 tion of charcoal which had been deposited on the wire during its 

 apparent extinction. 



This experiment, first made in the light, was repeated in a 

 dark room, and extended to ten, twelve, and eighteen hours. 

 When performed in absolute darkness, there were sometimes 

 extremely faint temporary emissions of light, which, I incline to 

 think, may have been occasioned by my breathing, or otherwise 

 agitating the external air, so as to produce irregular influxes 

 of it through my rude apparatus. 



The consumption of the alcohol is very trifling. On this and 

 other accounts, whenever not actual light, but the power of 

 producing light is the object, as daring night in a bed-room, the 

 lamp may be preferable in its apparently extinct state. Sir 

 Humphry Davy remarks, that " the chemical changes in 

 general produced by slow combustion appear worthy of investi- 

 gation : " possibly in this investigation the lamp may be of some 

 utility. " When the experiment of the slow combustion of ether 

 is made in the dark, a pale phosphorescent light is perceived 

 about the wire;" and with this appearance, he observes, is 

 connected " the formation of a peculiar acrid, volatile substance 



