94 EFFECTS of HEAT 



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 

 ftate. In many cafes I affifled the compactnefs of the tube by 

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

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



These devices anfwered the end propofed. Three-fourths 

 of the tube next the muzzle was found completely filled with 

 a. mafs, having a concave termination at both ends, f/and^ 

 figs. 17. 18. 19.)* fhewing that it had flood as a liquid in the 

 two 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 fubjecled to an unforefeen fource of 

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

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

 through which the borax and carbonic acid efcaped. I faw 

 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 introduction of a very fmall air-tube. 

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



In the courfe of the years 1801, 1802, and 1803, I made a 

 number of experiments, by the various methods above defcrib- 

 ed, amounting, together with thofe made in gun-barrels, to 

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

 which the apparatus was ftrained to the utmoft of its power, 

 conflant fuccefs could not be expe&ed, and in fact many expe- 

 riments failed, wholly or partially. The refults, however, upon 



the 



