Application of the Blow-p'ipe. 30 1 



Added to this, the charcoal was fo rapidly confumed, that the 

 fubrtance atled on became fo much buried, that it was diffi- 

 cult to follow it with the eye, or the orifice of the pipe: and 

 fome fubftanocs were obfer'ved to run into the pores of the 

 coal, and elude examination. 



To avoid thefe evils, it was thought defirable that means 

 might be difcovered of clothing the upper fiirface of any body 

 which might be fubjec\ed to this fpecies of operation with 

 fome burning matter, of which the heat might be equal to 

 that of the incandefcent carbon, with which the lower furface 

 might be in contaftj or by which bodies might be expofed 

 on^folid fupports to a temperature equal or luperior to thai 

 of the porous charcoal uniting with oxygen. 



It foon occurred that thefe tlefiderala might be attained by 

 means of flame fupported by the hydrogen and oxygen gafes ; 

 for it was conceived that, according to the admirable theory 

 of the French chemifts, more caloric ought to be extricated 

 by this than by any other combuliion. 



By the union of the bafes of the hydrogen and oxygett 

 gafes, not only is all the caloric of the oxygen gas evolved, 

 but alfo a much larger quantity, which mult be neccfliai-y to 

 give the panicles of the hydrogen their fuperior power of re- 

 ptilfion. The product of this combultion is water in the ftate 

 of (team, which retains heat fo (lightly, that it a6ls merely ab 

 a vehicle to deliver it to other bodies. What is neccilary to 

 preferve to water its form of fluidity, is the only portion of 

 the caloric extricated in this combuftion, wiiich is perma- 

 nently abftracled. 



The combullion of carbon with oxygen gas^has been 

 hitherto confidercd as the hotteft of all' Tires, The caloric 

 evolved in this cafe proceeds from rlic oxygen gas alone, 

 while the produd of this combuftion is carbonic acid gas, 

 -vhich abllradls the targe quantity of caloric, necelTary to give 

 it the form of permanent air, but which adds nothing to the 

 heat of the combuftion. Hence it i- evident, that more ca- 

 loric is evolved, and lefs abftrartcd, in combuftion fupported 

 by the hydrogen and oxygen gaf^'s, than in that fupported by 

 oxygen gas and carbon. 



However, the intenfenefs of the heat of combuftion Is not 

 only dependent on the (iuantil\ of caloric extrican J, but alfo 

 on the comparative fmalhicfs of ll)e time and fpace in which 

 the extrication is accomphflied. But iw this refpeft the 

 aiirifonn cotnbuftiblc has obvioufly the advantage over thofe 

 which are folid, as iis fluid and elaftic properties render it 

 fufccptible of bcinj* rapidly precipitated into the focus of 



conibuftion. 



