280 SCIENTIFIC NEWS. 



Flajh fro?n an Air-Gun. 

 Luminous fbfh M. Pi&et, in a letter from Paris of the 1ft of January lait 

 from an air gun. t0 Mr# Tl [\ och (PhiIof# Magazine, Vol. XIV. 363.) ftates a 

 communication to the National Inftitute of France on the 29th 

 of December by M. Mollet, of Lyons, refpe&ing the lumi- 

 nous appearance produced by the difcharge of an air-gun in 

 the dark, a phenomenon which he confiders as never having 

 been before obferved. It has, however, been known forfome 

 time in this country, having been firft mentioned, I believe, 

 near a year and a half ago by Mr. Fletcher at a meeting for 

 philofophical experiments and converfations, which was then 

 held weekly at my houfe. Several difcuffions accordingly 

 took place with regard to its caufe, — as, whether it was pro- 

 duced by electricity, or the change of capacity in the expand- 

 ing fluid, &c. and it was intended to inftitute a courfe of ex- 

 periments on the fubjeci, but fome other objects of enquiry- 

 intervening the matter was poftponed. It is a curious phe- 

 nomenon, and, deferves invefb'gation. 



Letter from Profeffor Proust to J. C. Delametherie. 

 On the Sugar of Grapes, and the Compound Nature of Uree. 

 Newfugarin I have difcovered a new fugar in the grape, which is the 



c grape. k a fo of wine ; it is different from that of the fugar>cane, cry- 



ftallifes differently, &c. It is contained in the proportion of 

 about 30 per cent, in the juice of the grape. Azote is uni- 

 formly combined with the carbonic acid in the fermentation of 

 wine: in that of gluten it is pure hidrogen, which is difen- 

 gaged with the carbonic acid. 

 The uree Is a Tell Vauquelin that the ur£e, in the ftate in which they 

 compound con- } lave examined it, is a faline fubftance faturated with ammonia, 

 nia. arid not a fimple product ; he need only apply fulphuric acid 



to carry off this ammonia, and to have the uree pure, but co- 

 loured with a refin from which I have not yet been able to 

 free it. 



J. de Phyfique. 



On 



