forms with perfea regularity. From this I concluded, that 

 when the whin congealed, which mufi have happened about 

 28'^ or 30" of Wedgwood, the fpar was ftill liquid. I therefore 

 expefted, if I could compel the carbonate to bear a heat of 28" 

 without decompofition, that it would enter into fufion. The 

 fequel will fiiew that this conjedure was not without foun- 

 dation, 



I fhall now enter upon the defcription of thofe experimentsj ^he ex- 

 the refult of which I had the honour to lay before this Society perimentsfn- 

 on the 30fh of Auguft laft (1804); fully aware how difficult ,V°'^""''* 

 is, in giving an account of above five hundred experiments, all 

 tending to one point, but dit!ering much from each otiier in 

 various particulars, to fteer between the oppofite faults of 

 prolixity and barrennefs. My objea Hiall be to defcribe, as 

 fliortly as pofTible, all the methods followed, fo as to enable 

 any chemift to repeat the experiments ; and to dwell particu- 

 larly on fuch circumftances only as feem to lead to Conclufions 

 pf importance. 



The refult being already known, I confider the account I 

 am about to give ot the execution of thefe experiments, as 

 addrefied to thofe who take a particular interefl in the progrefs 

 of chemical operations: in the eyes of fuch gentlemen, I iruft, 

 that none of the details into which I mul^ enter, will appear 

 fupert^uous. 



SECTrON II. 



Principle of Execution upon which the Jblloiving Experiments were 

 conduced. — Experi7nents with Gun. Barrels filled ivith baked 

 Clay, and welded at the Muzzle. — Method zvith the fufible 

 Metal. — Remarkable Effeds of its Expanfion. — Necejiij/ of in- 

 iroducing Air. — Befidts obtained. 



When I firft undertook to make experiments with heat 

 afting under compreffion, I employed n^yfelf in contriving "^^^ ^"'^^°'"'* 

 various devices of fcrews, of bolts, and of lids, fo adjufted, I t^vance" for 

 hoped, as to confine all elaftic fubfiances ; and perhaps (ome confining claftlc 

 of them might have anfwered. But I laid atSde all fuch de- highTempe- 

 vices, in favour of one which occurred to me in January 1798; tatures. 

 which, by its fimplicity, was of eafy application in all cafes, 

 and accompliflied all that could be done by any device, fince 

 h fecured perfei^ ftrength and tightnefs to the utmoft that the 

 veflels employed could bear, whether formed of metallic^or 

 earthy fuffiance. The device depends upon the following 

 general view ; If we take a hpllpw tube or barrel (AD PL ix. 



fig. 



