E 407 ] 

 LIV. Intelligence and Miscellaneous Articles. 



ON THE COMBUSTION OF GUNPOWDER in VaCUO, AND IN VARIOUS 

 GASEOUS MEDIA. BY M. BIANCHI. 



T HAVE the honour to lay before the Academy a resume of the prin- 

 -*- cipal results of my experiments on the combustion of powder in 

 air, and in various gaseous media. 



The apparatus I have used consists of a glass globe, in which, by 

 a socket and by means of a screw-thread, a support penetrates, 

 which can be adapted to the air-pump. This support is traversed 

 by two metallic rods with clamps, well insulated and intended to 

 receive a small crucible formed of platinum wire about half a milli- 

 metre in diameter, rolled in a conical spiral and closed by a cover, 

 also formed of platinum wire. In this crucible the powder is placed. 

 By means of a battery of three or four Bunsen's elements, the plati- 

 num wire which constitutes the crucible is heated to redness. The 

 principal facts observed may be summed up in the following 

 phenomena : — 



1. Ordinary powder, fulminates, and all gunpowders, in grains or 

 in compact masses, placed freely in vacuo, that is to say, in a great 

 space as compared with the volume of the powder, and submitted to 

 the sudden action of a heat of more than 2000°, burn slowly and 

 without producing, as in air, a brisk deflagration. 



2. On the contrary, when the powder is enclosed in a pistol and 

 also exhausted, and is ignited by means of a platinum wire raised 

 to redness, or, better, by a percussion cap, it explodes as rapidly as 

 in air. 



3. In vacuo the combustion of gun-cotton takes place slowly in 

 successive layers, commencing by the parts nearest the source of 

 heat ; once commenced, it continues until the gun-cotton com- 

 pletely disappears, without its being in contact with the incan- 

 descent focus ; lastly, this combustion takes place without producing 

 light, even in the greatest darkness. 



4. The products of combustion are not the same as in air. 



5. The combustion of powder takes place in nitrogen, carbonic 

 acid, and other gaseous media unfit for combustion, with a rapidity 

 and briskness almost equal to that in air. — Comptes Rendus, July 

 14, 1862. 



OBSERVATIONS ON THE SOLAR SPECTRUM. BY DR. A. WEISS. 



In former years I have repeatedly observed the condensation of 

 Fraunhofer's lines in the solar spectrum ; and a communication of 

 mine on this subject appears in the Philosophical Magazine, vol. 

 xxii. p. 80. I thought even then that I had discovered an analogy 

 with certain absorptions which I had observed in other spectra, and 

 I am glad to have had opportunity of confirming this view. 



In a journey to Greece in last year, in which I was provided with 

 a Soleil's spectroscope, I observed from the vessel as often as I could 



