300 Memoir on the Supply and 



«fe of atmofpheric air when the heat produced by it is 

 fiifficienily intenfe. h mult be obvious, if the conical 

 mouths, 0,0, of the pipes M, N, O, ni, n, o, fig. i, be fur- 

 iiifhed witli ftraight mouth-pieces, that any lamp or candle 

 placed on the Hand TV may be readily fliiftcd from one 

 mouth piece to the other, when it fhall be defircu to expofe 

 any fubjeil fucc-eflivcly to the heat produced by atmofpheric 

 air and oxygen gas. 



It it he wiflied to make ufe of the heat produced in the 

 combuftion of charcoal with oxvgen gas ; after having con- 

 fined a fufficicnt quantity of this gas, it will be neceilary to 

 fix in the conical mouth of the pipe, communicating with 

 the compartment containing the gas, the larger end of a 

 common brafs blow-pipe, the orifice being direclcd down- 

 wards. Under this orifice the body to be a6led on muft be 

 placed, fupported bv a piece of charcoal, in the form of a 

 parallelepiped, the charcoal being ignited in the part conti- 

 guous to the body. Things being thus arranged, by turn- 

 ing more or lefs the cock of the pipe in which the blow-])ipe 

 fhall be fixed, a fircam of oxygen may be precipitated on the 

 burning fpot, with the proper degree of rapidity *. 



This method of fupporting the combuftion of carbon with 

 oxygen gas is nearly the fiune as that by which the celebrated 

 Lavoifier performed his experiments; excepting that in the 

 place of the hydroftatic blow-pipe he made ufe"of his gafo^ 

 meter. 



In the ifitroduclion to this paper it was mentioned that 

 fome experiments had been performed which feemed to in- 

 validate the opinion that the employment of larger quantities 

 of oxygen gas would be the only means of increafing the 

 power of caloric. I fliall proceed to give an account of dief^ 

 experiments, but will firft retrace the ideas which led to thenu 



In operating with the combuftion of carbon and oxygen 

 gas, great evils were obferyed to refult from the difficulty of 

 placing the fubjed of the operation in the -focus of the heat, 

 without interrupting the liream of air by which this heat was 

 fupported. Not onTy was the focus widened by this interrup- 

 tion, and the intenfcnefs of the heat thereby Icflened ; but 

 the ftream of air oxidated thofe fubftances which were coni- 

 buftible, and coo'ed thofe whifh were otherwife, iii the places 

 where it impinged prpyiQufty to its union with the charcoal. 



* In (letailinj; the ufcs of tlie hydroftaric bicw-pipe, it may be proper 

 To mention rhu facilitv wbirh it gives to the cniploynient of the j;a(cs for 

 medical purpofcs. When this machine is filled witli any gas, the bag to 

 be made uie of in rcfpiring it may be inflated by fi.sjng it to the mouth of 

 the pip-, of deiivtry cyminunifating with the gui. 



Added 



