for the Comhujlhn of Phofphoms In Oxygeti Gas. 85 



iiJg glafs. I have obfervcd that phofphorus wrapt up in a 

 particular manner inflames Tpontaneoufly when the air is 

 rarefied to a certain desfree; and I employ the refult of thi^ 

 obiervation to inflame the phofphorus in the balloon. *. 



By means of this apparatus I have feveral times, both iit, 

 the courfe of my lefturcs and on other occafions, <hewn the 

 produdiion of the phofphoric acid by the combullion of 

 phofphorus in oxygen gas, a? defcri.bed by Lavoifier in the 

 Alemoirs of the Academy of Sciences for the year 1777, 

 ■(page 65.) In my experiments I have generally burnt fixty 

 grains of phofphorus. They have fliewn that the weight of 

 <he phofphoric acid produced is always nearly equal to that 

 of the phofphorus burnt, and of the oxygen gas employed. 

 I calculated the refults by the method defcribed by Lavoifier 

 in his Treatife of Chemiftry (vol. ii.) ; but it is not uecef- 

 fary they ihould be inferted here, as the compofition of 'the 

 phofphoric acid has been fufficiently eftablifhed by the accu- 

 rate experiments of Lavoifier, My objeft, in defcribing the 

 apparatus I employed, was merely to enable thoft who wifli 

 to repeat the experiments to do fo by an eafier method^, and 

 with more certainty than according to that propofed by him. 

 It muft here be obferved, that as the phofphorus, by my pro-r 

 cx'fs, inflames in rarefied air, there is no danger that thcfud- 

 den expanfion of the air, produced by tlie intenfe heat of 

 the inflamed phofphorus, will burft the glafs; to prevent 

 wliich, in Lavoificr's method, requires great caution, as he 

 himfelf has remarked. That the balloon during the com- 

 buftion may be as little heated as poflible, I fufl^er the air, 

 after the inflammation, to pafs gradually, and in fmall 

 (juantity, into the glafs globe, and for that reafon do not 

 open the cock until the flame begins to be extinguiflied-. In 

 tiiis manner the experiment ?nay be performed without any 

 danger. 



In the year 1794 I made known, in the thirteenth num- 

 ber of the Chcnnfclai Ocj]^£tihige7i of the celebrated Kafiel- 

 G 3 lyn^ 



