MODIFIED by COMPRESSION. 133 



thus efcape without proving the main point under confidera- 

 tion, namely, their fufion. 



The reft of the apparatus was arranged in all refpects as 

 formerly defcribed, the fame precautions being taken to defend 

 the platina veftel as had been ufed with the inner tubes of 

 porcelain. 



In this manner I have made a number of experiments 

 during this fpring and fummer, the refult of which is highly 

 fatisfa&ory. They prove, in the firft place, the propriety of 

 the obfervations which led to this trial, by fhewing, that the 

 pure carbonate, thus defended from any contamination, is 

 decidedly more refractory than chalk; fince, in many ex- 

 periments, the chalk has been reduced to a ftate of marble, 

 while the pure carbonate, confined in the platina vefTel, has 

 been but very feebly acted upon, having only acquired the in- 

 duration of a fandftone. 



In other experiments, however, I have been more fuccefs- 

 ful, having obtained fome refults, worthy, I think, of the at- 

 tention of this Society, and which I fhall now fubmit to their 

 infpeclion. The fpecimens are all inclofed, for fafety, in 

 glafs tubes, and fupported on little ftands of wax, (fig. 31, 

 32, 33.). The fpecimens have, in general, been removed from 

 the cup or tube of platina in which they were formed, thefe 

 devices having the advantage of fecuring both the veflel and 

 its contents, by enabling us to unwrap the folds without vio- 

 lence ', whereas, in a folid cup or tube, it would have been dif- 

 ficult, after the experiment, to avoid the deftru&ion either of 

 the veflel or its contents, or both. 



April 16. 1805. — An experiment was made with pure 

 calcareous fpar from St Gothard, remarkably tranfparent, and 

 having a ftrong double refraction. A temperature of 40 was 

 applied 3 but owing to fome accident, the weight was not 

 known. The conical cup came out clean and entire, filled 



not 



