MODIFIED ly COMPRESSION. I4t 
Ir was effential, in this mode of operation, that the whole. 
of the metal fhould continue in a liquid ftate during the action: 
of heat; but when I was fatisfied as to its intenfity and dura- 
tion, I congealed the metal, either by extinguifhing the furnace 
entirely, or by pouring water on the barrel. As foon as the 
heat began to act, drops of metal were feen to force themfelves- 
between the barrel and the leather, following each other with. 
more or lefs rapidity, according to. circumftances. In fome. 
experiments, there was little exudation; but few of them 
were entirely free from it. LTofave the metal thus extruded, 
I placed.a black-lead crucible, having its bottom perforated, 
round the barrel, and. luted clofe to. it, (fig. 37.); fome fand. 
being laid in this crucible, the metal was. collected on its fur-- 
face. On fome occafions, a. found of ebullition was heard. 
during the action of heat; but, this was.a certain fign of. fail-- 
ure. rt we 
THE refults. of the moft important of thefe experiments,. 
have been reduced to a common ftandard in the fecond table: 
placed in the Appendix ; to which reference is.made by the. 
following numbers. 7 
No. 1.—Own the 16th of June'1803; I made an experiment. 
with thefe arrangements. I had tried to ufe a weight of 30lb.. 
producing a preflure of 90 lb., but I found this not fufficient. 
I then hung on.a weight of 1 cwt., or 112.1b.; by. which a com-. — 
prefling force was applied of : 3.cwt. or, 3361b. Very little: 
metal was feen to efcape, and no found of ebullition was heard. 
‘Fhe chalk in. the body of the large tube was. reduced to quick- 
lime ; but what lay in the inner tube was pretty firm, and ef- 
fervefced to thelaft. One or two facettes, of good appearance, 
were likewife found. The contents of the {mall tube had loft. 
but 2.6 per cent.; but there was a fmall vifible intrufion of me- 
tal, and the refult, by its appearance, indicated a.greater lofs. 
L.confidered. this, however, as one point gained ; that being the 
