COMBINATION "OF GASES, &C. 0\3 



great attention he paid in caufing the requifite preparations to 

 be made, and for hisperfonal affiftance in repeating it. 



We took the fyringe of an air-gun, the bottom of which Experiment In 

 was clofed by a very thick' glafs, in order that we might ob- j^ngeof an air-" 

 ferve the light difengaged as ufual by compreffion. This fy-*gun filled up fo 

 ringe was of iron : it had a cock on one fide to introduce the as , t0 reC j ,V j th „ e 



? m * gales and admit 



gates, and its lower extremity on the fide of the pifton was or infpeaion 

 enveloped by a cylinder of lead, fufficiently weighty to acce- mto its chamber, 

 lerate the fall and render the compreffion more rapid. This w ith common 

 apparatus was firit tried by introducing atmofpheric air ; but air > 

 though the experiment was made in the dark, no perceptible 

 light was feen, probably becaufe the violent motion neceflary 

 for the rapid compreffion, prevented the operator from look- 

 ing fo directly through the glafs as to perceive the tranfient 

 light which compreffion difengages, and which I myfelf had 

 feveral times feen. -non-Mfm 



Immediately after this trial a mixture of hidrogen and oxigen and afterwards 

 r i i - . „t ■'..«, v,a .- ,,• i n i • with a mixture 



-gales was introduced into the fyringe, and a itroke was given. o{ ox ; gen an d 



An extremely brilliant light appeared with a loud detonation : hidrogen. 

 The glafs bottom was driven out: The copper fcreW which ?,jfc e ab ^ 

 retained it in its place was broken ; and the perfon who held ftrong luminous 

 the fyringe had his hand (lightly burned and wounded by the explofion. 

 force of the explofion;" 



The experiment was repeated, by fubilituting a brafs bot- Repetition with 

 torn of one entire piece fere wed on inftead of that of glafs. ThTfvringe^* 

 and a new mixture of the gafes was introduced. The firft burft. 

 tiroke of the pitlon produced an explofion, which was heard 

 like the loud crack of a whip ; but a fecond itroke with a new 

 charge of the gafes, cauled a detonation which broke or rather 

 tore the body of the fyringe with a violent explofion. 



After thefe phenomena there can remain no doubt respect- 

 ing the combination of the two gates;' as it is known that 

 this combination produces the detonation by the immenfe 

 quantity of heat difengaged when they pals to the liquid 

 liate; a heat which is fufficient to reduce them immediately 

 into vapour, and give them an exceffive dilatation in that 

 ftate. It was not therefore thought neceflary again to repeat ^^^ 

 this experiment, which is attended with fome danger. 



^JH^The theory of thefe phenomena is extremely rimple. A Theory, the 

 rapid compreffion forces the gafes ta abandon- a ^erygre«t| nfes k ive out 



it»Hiw»T 5 quantity 



