MODIFIED b) COMPRESSION. 133 
thus efcape without proving the main — under coriliderae 
tion, namely, their fufion. 
Tue reft of the apparatus was ccntcieael in’ all refpects as 
formerly defcribed, the fame precautions being taken to defend 
the platina veffel as had ‘been ufed with the inner tubes of 
porcelain. © 
In this manner I ord made a number of experiments 
during this {pring and fummer, the refult of which is highly 
fatisfactory.. They prove, in the firft place, the propriety of 
the obfervations which led to this trial, by fhewing, that the 
pute 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 veflel, 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 
infpection: 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 deftruction either of 
the yeflel or its contents, or both. 
Aprit 16, 1805.—An experiment was made with pure 
calcareous {par from St Gothard, remarkably tranfparent, and 
having a ftrong double refraction. A temperature of 40° was 
applied; but owing to fome accident, the weight was not 
known. The conical cup came out clean and entire, filled 
not 
