266 Experiments refpecllng Heat. 



In a few feconds after opening the communication with 

 the gafometer, fuch a vivid flame iflued through the hole in 

 the cover of the furnace, that it was thought unneceffary to 

 carry the procefs further, as the gas appeared evidently to 

 be acling on the fuel in the furnace, inftead of having its 

 action confined principally, as was intended, to the contents 

 of the crucible. 



After fome time, the furnace was examined. More than 

 a half of the clay tube which ferved to convey the gas 

 through the furnace into the crucible was found gone, and 

 the remaining portion of the tube poliihed highly on the 

 furface, the clay having been running in a Hate of extreme 

 fufion. The fide of the crucible next the tube was polifhed 

 in the fame manner, and the hole in which the tube had 

 been luted was found greatly enlarged. The charcoal in the 

 crucible had not been half confumed, and the platina was 

 found fufed at the bottom. A few globules were found iu- 

 terfpened among the charcoal, having been arreiled in their 

 defcent by flopping the procefs before they had time to reach 

 the chief mafs at the bottom ; but it feemed plain that, had 

 the blah 1 of oxygen gas been continued for a minute or two 

 longer, the crucible would have been completely run down. 



The platina was then examined, but the refult was not 

 what the Society had promifed themfelvcs. Though it had 

 been completely fufed, the procefs was found to have been ot 

 too fhort a duration to oxydate all the iron contained in it. 

 The large button broke under the hammer. 



From this it appears that, though platina, in fmall quanti- 

 ties (Exper. XXXI.) may be reduced and brought to a flat? 

 of purity by oxydating the iron by means of a itream of oxy- 

 gen gas, it will require a confiderable degree of addrefs to be 

 able to apply this on a fcale of any confiderable extent. If 

 even rock-crvftal, and thofe gems which, till thefcexperi- 

 ments, have been held infufible, are yet found fufible by the 

 powerful heat excited by the agents employed in them, how 

 are materials to be obtained furficiently refractory to main- 

 tain the neceffary arrangements in a furnace during fuch a 

 procefs ? 



VIII. 4* 



