474 Experiments en the Fufion of Platina. 



to fufe It in the fame fized crucible he had ufed, 

 but the operation failed. It was tried a fecond 

 tinne, on account of the laft operation being 

 fhortened a quarter of an hour, but with no bet- 

 ter fuccefs. On the third trial it was put in a 

 fnnaller crucible, and ftill the operation failed. 

 There was a ftrong agglutination, but not a per- 

 fcft fufion. The conjefture of the caufe of this 

 failure will be mentioned hereafter. 



Mr. Henry, junior, was prefent at all the ope- 

 rations mentioned under experiment eighth, and 

 Wedgwood's pyrometer pieces were put into 

 each crucible to afcertain the degrees of heat. 



In this and all the experiments before-men- 

 tioned the fire was not remarkably ftrong, but in 

 feeding it with cauk, care was taken that it never 

 burnt fo low as to fall much below the upper 

 part of the inverted crucible, and no fuel was 

 added, which had not been previoufly heated 

 on the iron plate which covered the furnace. 



The pyrometer piece indicated i6o° in the 

 laft operation that mifcarried, and in the other 

 two the fire was at leaft 140' to 150®. 



EXPERIMENT IX. 



One ounce of platina was placed on a bed of 

 pulverifed Welch coal, in the fame manner as 

 in the former experiments with charcoal, and an 

 uniform fufion was in one hour and a half effefted. 

 It mwft be obferved, that in all thefe operations 



the 



