BY COMPRESSION, 385' 



tlie fire. In confequence of this, the borax was feen from 

 above lo melt, and run clown in the tube, the air contained in 

 the powder efcaping in the forni of babbles, till at laft the 

 borax llood with a clear and Ready furfacc like that of water. 

 Some of this fait being thrown in from above, by means of 

 a tube of glafs, the liquid furface was raifed nearly to the muz- 

 zle, and, after all had been allowed to become cold, the po- 

 lition of the tube was reverfed ; the muzzle being now plun- 

 ged into the fand, (as in fig. 17.) and the breech introduced 

 into the muffle. In feveral experiments, I found it anfwer 

 well, to occupy great part of the fpace next the muzzle, with 

 a rod of fand and clay previoufly baked, (fig. 19. KK), which 

 was either introduced at firft, along with the pounded borax, 

 or, being made red hot, was plunged into it when in a liquid 

 fiate. In many cafes I aflifted the compadnefs of the tube by 

 means of an internal glaze of borax ; the carbonate being pla- 

 ced in a fmall tube, (as fliewn in fig. 18.) 



Thefe devices anfwered the end propofed. Three-fourths Effect of ex- 

 of the tube next the muzzle was found completely filled with 5^"^*°" '" ^^^ 

 a mals, having a concave termmation at both ends,,-{/ and g upon the tubes, 

 figs. 17, IS, 19.) ftiewing that it had flood as a liquid in the 

 (wo oppofite pofitions in which heat had been applied to it. 

 So great a degree of tightnefs indeed was obtained in this 

 way, that I found myfelf fubjefled to an unforefeen fource of 

 failure. A number of the tubes failed, not by explofion, but 

 by the formation of a minute longitudinal fiffiire at the breech, 

 through which the borax and carbonic acid efcaped. I favsr 

 that this arofe from the expanfion of the borax when in a li- 

 quid ftate, as happened with the fufible metal in the experi- 

 ments with iron-barrels; for, the crevice here formed, indi- 

 cated the exertion of fome force acting very powerfully, and 

 to a very fmall diftance. Accordingly, this fource of failure 

 was remedied by the introduiftion of a very fmall air-tube. 

 This, however, was ufed only in a few experiments. 



In the courfe of the years 1 801 , 1 802, and 1S03, I made a Thefe experi- 

 number of experiments, by the various methods above defcrib- fn<^nt* were 

 ed, amountmg, together with thole made in gun barrels, to fuccefsful. 

 one hundred and fifiy-fix. In an operation fo new, and in 

 which the apparatus w-as firained to the utmofl of its power, 

 confiant fuccefs could not be expelled, and in fact many expe- 

 riments failed, wholly er pariially. The refults, however, 

 2 upon 



