134 EFFECTS of HEAT 



not quite to the brim with a yellowifh-grey fubfiance, having 

 a mining furface, with longitudinal ftreaks, as we fometimes fee 

 on glafs. This furface was here and there interrupted by lit- 

 tle white tufts or protuberances, difpofed irregularly. On 

 the ledge of the cup, formed by the ends of the folded plati- 

 na, were feveral globular drops like minute pearls, vifible to 

 the naked eye, the number of which amounted to fixteen. 

 Thefe feem to have been formed by the entire fufion of what 

 carbonate happened to lie on the ledge, or had been entangled 

 amongft the extremities of the folds, drawing itfelf together, 

 and uniting in drops ; as we fee when any fubltance melts un- 

 der the blowpipe. This refult is preferved entire, without de- 

 ranging the tube. I am forry to find that it has begun to fall 

 to decay, in confequence, no doubt, of too great a lofs of its 

 carbonic acid. But the globules do not feem as yet to have fuf- 

 fered any injury. 



April 25. — The fame fpar was ufed, with two grains of 

 water, and a heat of 33 . I have reafon to fufpecl:, how- 

 ever, that, in this and feveral other experiments made at 

 this time, the metal into which the cradle was plunged, on 

 firft introduction into the barrel, had been too hot, fo as to 

 drive off the water. There was a lofs of 6.4 per cent. The 

 refult lay in the cup without any appearance of frothing 

 or fwelling. The furface was of a clean white, but rough, 

 having in one corner a fpace mining like glafs. The cup 

 being unwrapt, the fubfiance was obtained found and entire : 

 where it had moulded itfelf on the platina, it had a fmall de- 

 gree of luftre, with the irregular femitranfparency of faline 

 marble : when broken, it preferved that character more com- 

 pletely than in any refult hitherto obtained ; the fracture be- 

 ing very irregular and angular, and mining with facettes in 

 various directions. I much regret that this beautiful fpecimen 



no 



