hV COMPRESSION, 337 



of the barrel, by means of a plug, fixed by folder only; which me- 

 thod bad this peculiar advantage, that I could (hut and open the 

 barrel without having recourfe to a workman. In thefe trials, 

 though many barrels yielded to the expanfivetbrce, others refifted 

 it, and afforded fome refults that were in the highert degree en- 

 couraging, and even falisfa^ory, could they have been ob- 

 tained with certainty on repetition of the procefs. In many 

 of them, chalk, or common limeftone previoufly pulverifed, Satisfaflory ' 

 was agglutinated into a ftony mafs, which required a fmart '^^'^"'"* 

 blow of a hammer to break it, and felt under the knife like a 

 common limeftone; at the fame time, the fubftance, when 

 thrown into nitric acid, difiblved entirely with violent efFer- 

 vefcence. 



In one of thefe experiments, owing to the adion of heat on Volatile matte- 

 the cartridge of paper, the baked clay, wliich had been ufed '"ay be drivea 

 to fill the barrel, was ftained black throughout, to the dillance anoTher part of 

 iOf two-thirds of the length of the barrel from its breech. This a clofed barrel. 

 •circumfiance is of importance, by lliewing, that though all is 

 tight at the muzzle, a protrufion may take place along the 

 barrel, greatly to the detriment of complete compreffion : and, 

 at the fame time, it illuftrates what has happened occaftonally 

 in nature, where the bituminous matter leems to have been 

 driven by fuperior local heat, from one part of a coaly bed, 

 though retained in others, under the fame compreffion. The 

 bitumen fo driven off being found, in other cafes, to pervade 

 and tinge beds of flate and of fandftone. 



I was employed in this purfuit in fpring 1800, when an 

 event of importance interrupted my experiments for about a 

 year. But I refumed them in March 1801, with many new 

 plans of execution, and with confiderable addition to my ap- 

 paratus. 



In the courfe of my firft (rials, the following mode of execu- ^Jfpenments in 



1 . I IT 1 • -,- which the 



tion had occurred to me, which I now began to put in practice, fufibie metal 



It is well known to chemifts, that a certain compofilion of ^^^ "^^^ " th« 



plug. 



force of comprefTion. I have fyice made great ufe of this valuable 

 fuggeftion : but he fcarcely li^ed, alas ! to fee its application ; for 

 my firft faccefs in this way took place dyring his laft illnei's.— I 

 have been expol'ed to no rifk in any other experiment with iron 

 liarrels} matters being fo arranged, that the ftrain againft them has- 

 only commenced in a red heat, in which the metal has beeo fo far 

 foftened, as to yield by laceration like a piece of leather. > - 



different 



