ly the mere Compression of Atmospheric Air. 131 



piece of amadou* placed within the canal of the pump. 

 And if the instrument be furnished by a lens firmly secured, 

 a vivid flash of light is said to be perceived at the instant 

 of this condensation. The evolution of light seems to have 

 been first noticed by a workman employed in the manufac- 

 ture of arms at St. Eticnne, who discharged an air gun 

 highly loaded, observed a vivid flash at the orifice of the 

 barrel. 



These curious discoveries of the foreign philosopher have 

 lately been applied to piactical utility in this country. In- 

 genious workmen have shown, that for the accension of 

 combustible bodies by compressed air, the air gun is by no 

 means necessary, but that the experiment may be performed, 

 3nd even with more ease, by means of a common condens- 

 ing syringe of good workmanship. The number of insiru- 

 ments of that kind which have been called for at my labo- 

 ratory, and with which the scientific public has been sup- 

 plied, gives me reason to think, that men of science deem 

 this simple apparatus worthy of notice. The instrument I 

 have furnished consists of a common syringe, as usually sold, 

 about ten inches long, and not more than -| of internal bore. 

 At the lower extremity it is furnis-hed with a cap, which 

 serves as a chamber to receive the substance intended to be 

 fired, and which cap is attached to the instrument by a male 

 and female screw, or instead of this cap a common stopcock 

 may be used ; the former contrivance, however, is more 

 elegant, more durable, and less expensive. 



To use \.\m instrument the cap is unsciewed, or the stop- 

 cock turned, a small piece of amadou or common tinder is 

 placed in the chamber, and the cap screwed on acain. If 

 the piston of the instrument be now depressed with as quick 

 a motion as possible, the condensation of the air is so ac- 

 tive as to set the amadou on fire. 



From the result of a few experiments which T have made 



• The name amaihju h given to a kind of tinder which is imported from 

 Oprmauy. It is made of a large fungus, which grows on old trees, cspeci,illy 

 on the oak, ash, and tir. Thia substance, being first boiled in common water, 

 aiul afterwards dried ..nd well beaten with a mallet, it theo soaked in a solu- 

 tii>ii of saltpetre, and again put to dry in an ov«a. 



I * with 



