502 JdlfeNtltlC NEWS* 



Experiment on the Heed which is developed during the Comprdjjioii 

 of the Air *, 

 Heat by com- A VERY curious experiment has been lately repeated be- 

 pttflionofair. fere the National Inflitute. If the air be very rapidly com- 

 prefled in the ball of an air gun, a conliderable quantity of 

 heat is difengaged from the firft flroke of the pifton, which is 

 fo great that it is capable of fetting fire to a piece of fungus 

 match (amadou) placed within the pump. If the body of 

 the pump be terminated by a moveable end formed of a piece 

 of (lee! firmly fere wed in, and furniftied in its centre with a 

 glafs lens, which admits of the infide being feen, at the firft 

 itroke of the pifton, a ray of vivid brilliant light will be per- 

 ceived, which is fuddenly difengaged. 



This obfervation is owing to accident ; it was made for the 

 firft lime by a workman in the raanufa6lure of arms of Saint 

 Etienne, who, on difcharging an air gun in which the air was 

 ftrongly coraprefled, perceived a very fenfible light at the end 

 of the barrel. 



Exirad of a Letter from Vrofessor Proust to J. C. Dela- 



METHERIE f. 



AMONG the memoirs which I have had for a long while 

 to fend to you, you will find one on Berth ollet's work, and on 

 what he fays of the hydrates, and alfo theanalyfis of a ftone 

 fallen from the atmofphere, at Sigena, in Arragon, which was 

 found to be perfedly fimilar to all thofe which have been hi- 

 therto analyzed. 

 iJrindy from the I do not know whether I ftiould mention to you a fort of 

 e«robctrcc. difcovery, which, however trifling it may appear to be, will, 

 neverthelefs be one day of great importance in Spain, parti- 

 cularly in the provinces where the carobe tree (carouhier) is 

 cultivated. It is known that the fruit of this tree is only cul- 

 tivated along all the coaft of the Mediterranean, to feed cattle. 

 However, after a fuitable fermentation it yielded me a quar^ 

 tillo (about the bulk of a pound of water) of excellent brandy, 



* Bulletin des Sciences, III. p. 209. The latter obfervation of 

 the flafh from an air-gun has been feveral times obferved before : See 

 our Vol. IV. p. 280. It Angularly contrafts the former fa£V. N, 



^ From Journal de Phylique, &c. Meflidor, An, XII. 



Dutch 



