7ieiv Mode of producing Fire. 9 



the hook of the piston, it usually becomes ignited at the first 

 stroke, by a most vivid flash. When the amadou is not used, 

 a more powerful stroke is necessary for the production of 

 light ; and when the piston is perfectly clean, one may some- 

 times repeat the experiment ten times before that effect is pro- 

 duced. 



The smallest piece of amadou, however, fixed to the hook 

 of the piston, facilitates the evolution of the light, and heightens 

 its brilliancy. Care only is to be taken that it may con- 

 tain many fibres, and for that reason it should not be com- 

 pressed with the fingers. It is strikingly manifested by this 

 experiment that the amadou does not act a merely passive part 

 when ignited by the flash, but that it contributes to the easier 

 excitement of the light, which is too brilliant to be mistaken 

 for the weak combustion of some points of the amadou, 

 when glowing under the smoke. There can be no doubt that 

 this is the fact, when we compare the experiment with those 

 of Mr. Hart already cited. Now it is well known that the 

 projecting fibres of amadou best adapt it for the absorption 

 of electricity. It was lately announced in a French Journal, 

 that this substance is particularly remarkable for this property 

 of drawing electricity from electrified bodies, and that with ra- 

 pidity and in great quantity: and MM. Lefevre-Gineau and 

 Pouillet have actually found that a piece of this substance ab- 

 sorbs electricity, when placed opposite to a charged conduc- 

 tor, at a greater distance than even a metal point. If it be 

 made wet, however, this property, which evidently arises from 

 its fibrous and spongy structure, becomes diminished*. 



The amadou in the apparatus for producing fire by compres- 

 sion above described, operates altogether with the same modi- 

 fications. I substituted for it metallic points, and they also 

 appeared to a considerable degree to favour the appearance of 

 light, though not to the same extent, as the action on such 

 tender electrical crystals as our theory supposes to exist in 

 elastic fluids depends so much upon the softness and abund- 

 ance of the points. 



Now let a metallic amadou be conceived ; that is, the effect 

 of metallic points united with the spongy structure; and this 

 moreover in a metal, like platinum, easily ignited by electri- 

 city f; will not such a metallic sponge greatly facilitate the 



development 



• See Gilbert's Annalen, band 73; or the new series, band 13, p. J27- 

 + While copper is easily melted in a moderate fire, and platinum is in- 

 fusible, they become reversed with respect to electric fire ; from which lat- 

 ter circumstance it h;is usually been concluded, that copper is a far better 

 conductor of electricity than platinum, which of all the metals is also the 



Vol. 64-. No. 315. July 1824.. B worst 



