N 
MODIFIED ly COMPRESSION. 79 
ous particulars, to fteer between the oppofite faults of prolixity 
and barrennefs. My object fhall be to defcribe, as fhortly as 
poffible, all the methods followed, fo as to enable any chemift 
to repeat the experiments ; and to dwell particularly on fuch 
circuraftances only, as feem to lead to conclufions of eli 
ance. 
TueE refult being already known, I confider the account J am 
about to give of the execution of thefe experiments, as addref- 
fed to thofe who take a particular intereft in the progrefs of 
chemical operations: in the eyes of fuch gentlemen, I truft, 
’ that none of the details into which I muft enter, will appear fu- 
s 
perfluous. 
Il. 
Principle of execution upon which the following Experiments were con- 
dutted.— Experiments with Gun-Barrels filled with baked Clay, and 
welded at the muzzle. —Method with the Fufible Metal.—Remarkable 
| effects of its expanfion, Sr Wee ty of introducing Air.—Refults ob- 
tained. 
Wuen I firft undertook to make experiments with heat 
ating under compreflion, I employed myfelf in contriving 
various devices of fcrews, of bolts, and of lids, fo adjuft- 
ed, I hoped, as to confine all elaftic fubftances; and per- 
haps fome of them might have anfwered. But I laid afide 
all fuch devices, in favour of one which occurred to me in 
January 1798; which, by its fimplicity, was of eafy appli- 
cation in all cafes, and accomplifhed all that could be done 
by any device, fince it fecured perfect firength and tightnefs to 
the utmoft that the veffels employed could bear, whether form. 
ed of metallic or earthy fubftance. The device depends upon 
: the 
