MODIFIED ly COMPRESSION. 145 
making the whole ten feet in length. In this manner, a pref- 
fure upwards was applied to the barrel, equal to the weight of 
TO cwt. 
In the former method, in which the barrel ftood with its 
muzzle upwards, the weight was applied while the metal was 
liquid. In this cafe, it was neceflary to let it previoufly con- 
geal, otherwife the contents would have run out in placing the 
barrel in the muffle, and to allow the liquefaction eflential to 
thefe trials, te be produced by the propagation of heat from 
the muffle downwards. This method required, therefore, in 
every cafe, the ufe of an air-tube; for without it, the heat 
acting upon the breech, while the metal at the muzzle was 
ftill cold, would infallibly have deftroyed the barrel. A great 
number of thefe. experiments -failed, with very confiderable 
wafte of the fufible metal, which, on thefe occafions was nearly 
allioft. But a few of them fucceeded, and afforded very fatis- 
factory refults, which I fhall now mention. 
In November 1803, fome good experiments were made in 
this way, all with a bore of 0.75, and a preffure of 10 cwt. 
No. 3.—Ow the 19th, a good limeftone was obtained in an 
experiment made ina a of 21°, with a lofs of only 
I.I per cent. 
No. 4.—On the 22d, in a fimilar experiment, there was 
little exudation by the muzzle. The pyrometer gave 31°. 
The carbonate was in a porous, and almoft frothy ftate. 
No. 5.—In a fecond experiment, made the fame day, the 
heat rofe to 37° or 41°. The fubftance bore ftrong marks of 
fufion, the upper part having fpread on the little tube: the 
whole was very much fhrunk, and run againft one fide. The 
mafs fparkling and white, and.in a very good ftate. 
No.6.—On the 25th,an experiment was made with chalk,and 
fome fragments of {nail fhell, with about half a grain of water. 
‘The heat had rifen to near 51° or 49°. The barrel had been 
Voi, VI.—P. I. F. held 
