z54 Experiments rcfpePang Heat. 



lofe of weight. It exactly rcfunblcs a pearl from a common 

 oyfter, or " dead pearlj" as jewellers term it. 



XXV. Another emeraid, weighing "ths of a carat, being 

 treated for the fame length of tune, prefehts the fame appear- 

 ance as the former, except tha! about one half of the globule 

 ftill retains Come traces of its original colour, and is. now of a 

 grcenifli gray. 



Cbrvfolite. 



XXVI. A cbrvfolite, weighing -' 6 tbs of a carat, being 

 treated during 2 loft no weight, but became fuled into a 

 rough opake grcenifli black globule. 



Jacinth. 



XXVII. Onejacynth, weighing **ths of a carat, treated 

 for \' 14" loft no weight, but became fufed into a globule 

 much rcfcmblinjr one of dark coloured bottle-elafs. but nearlv 

 opake. 



Opal. 



XXVIII. An opal, weighing ^ths of a carat, treated for 

 44" melted into a poiifhed globule of a greenith white almoft 

 tranfparent, but full of fmall bubbles. It loft no weight. 



Crvjlals. 



XXIX. A cut white crvilal, weio'hinc; £|<ths of a carat, 

 treated 1 '44" melted into a perfectly tranfparent globule like 

 flint glafs, but full of cracks and bubbles. Its weight is the 

 fame as before. 



XXX. Two fragments of rock-cryfial, weighing together 

 i;,*carat, expofed to the heat during 5' 19" melted together, 

 but flew to pieces on copling, and the whole is now in fe- 

 veral fragments; I'ome of it even in powder. It refembles a 

 very pure white fait. 



Plathia. 



XXXI. Sixteen carats of platina in grains, in the crude 

 ftate, were perfectly fufed in a few feconds. A fecohd and 

 a third quantity were likewife fufed ; but the circumftance 

 mod remarkable was, that the globules thus formed were 

 found to be pure and malleab'e. On examining them at- 

 tentively it was found that the iron, which is always prefent 



in 



