Application of the Bloiv-plpi. 303 



as when liahted formed a flame fmallcr in fize than that of 

 a candle. Under this Hanie was placed the body to he acSled 

 on, fupported cither by charcoal or by fome more foiid and 

 incombultible fiibllance. The cock retaining the oxygen gas 

 was then turned, until the light and heat appeared to have 

 attained the greatcfl: intenfity. When this took, place, the 

 eyes could fcarcely fuflain the one, nor could the moft refrac- 

 tory fubftances refift the other. 



However, it is worthy of notice that the light and heat of 

 this combullion do not become evident until fome body is 

 expofed to it, from which the light mav be refleSed, or oa 

 which the effeft of the heat may be vifible. This is not tlie 

 cafe with combnftion lupportcd by oxygen and carbon; for 

 no fooner is a ftream of oxygen gas direfted on ignited car- 

 bon, than an etfalgence is produced, which imprefi'es the 

 mind of the beholder with an idea of the greateft heat being 

 produced by it. 



It is in this different appearance of thefe different fpecies 

 of combullion that we may difcover the reafon why philofo- 

 phers have neglected the one, while they have bellowed much 

 attention on the other *. 



In lieu of the conical fruflum reprefentcd at cd, that at 

 de may be ufed. The tubular holes of this la(l-mentioned 

 fruftum do not meet, but deliver their air, at feparate orifices, 

 into an excavation in the lower part of the fruftum. The 

 dotted lines reprefent the tubular holes, and the arched line 

 ihe excavation. This is about three lines in diameter, and 

 enters into the filver about the fame diltance. 



At f are reprefentcd pipes which are ufed for the fufion of 

 platina, or fuhjedts of the larger kind. They confill of a large 

 and a fmall pipe, the orifice of the one being inferted into 

 that of the other, as may be underftood from the dotted lines 

 near f. 



The purity of gafes contained in the hvdroftatic blow-pipe 

 niav be at any time examined by chargmg eudiometers from 

 tlu lyphon and leathern pipes hanging to the cocks ZZ, fig. r, 

 'ilicle cocks are foldered to curved pipes, one of which ii* 

 reprefentcd in the figure. By turning the cocks round, the 



• TSic inferiority of the light emitted by the flame of the hydrojnn and 

 ovvgen gafes, to that which irradiates from bodies expofed to its iuSlion, 

 adds one to tlie many inft;mccs in tonibultion in which the qiiantiiy and 

 t'.'iiur «f the light extricated do not feein to be to mucii dependent on the 

 •).i;intity of oxygen gas coiifiuntd,;ison the nature of ilie fubftaiices he:itcd 

 "f burned. In this, therefore, v.e mny find fupport for the idea, tli.-it the 

 light extricated by fire, or emirted by Lfattd bodies, proectdsnct only 

 ffi/cn tlie dcconipofition of pure air, but from that oi the tonibuliibic, uc 

 {he heated bodies theairclves. 



mouths 



