Experiments rcfpeflhig Heat. 0,5 j 



in crude platina, and which, by adhering to it with great 

 abftinacy, makes it difficult to obtain that metal in its pure 

 ftate, was completely oxvdated, and adhering fo loofely to 

 the furface of the globules that it feparated itfelf in fcale's 

 when they were ftruck with a hammer. The globules were 

 then extended under the hammer without breaking. 



From this experiment it appeared probable that means 

 might be deviled to fufe large quantities of crude platina, 

 and at the fame time to obtain the metal pure and malleable; 

 an object fo delirable, that the Society relblved at leaft to 

 make the attempt". 



XXXII. A table furnace was conftructed in fuch a man- 

 ner, that (he crucible containing the platina (eight ounces) 

 could be brought to a flrong heat, by means of charcoal all 

 round it and a pair of double bellows, before allowing the 

 ftream of oxygen gas to be introduced into if.^ The platina 

 was put into the centre of the crucible, with charcoal below 

 and all round, in fuch a manner that the crucible was filled 

 . with the charcoal and the metal. The cover was luted on, 

 and a tube, made of burnt clay, which palled from a hole 

 near the bottom of the crucible to the outfide of the furnace, 

 was firmly luted into the crucible, which was fupported in, 

 the middle of the furnace. The clav tube was connected, by 

 means of another tube, with the large gafometer, and that 

 again with a feries of calks filled with oxygen gas. 



After exciting, by means of the double bellows, the fire 

 round the outfide of the crucible, till it was thought the criw 

 cib'c and its contents mull have attained the utmolt. decree 

 of heat that could in this way be obtained, the communica- 

 tion between the gafometer and the interior of the crucible 

 pened, and a lircam of oxygen gas forced in through the 

 clay tube among the contents of the crucible. 



It will be obferved from what has been ftaled, that the in- 

 tention was not to excite the fire in the body of the furnace 

 by means of a flream of oxygen. That appeared to be an 

 unneceffary wafte. All that was aimed at was, by exciting 

 a hidden, and rapid cotnbuftion of the charcoal lodged in the 

 crucible along with the platina, to reduce the latter; and it 

 was thought that the previous ignition of the crucible and its 

 contents, by the help of the furnace, would facilitate this. 



Vol. Viil. Mm In 



