igs Effects of Heat modified hij Compression. 



in the two opposite positions in which heat had been applied 

 to it. So great a degree of tightness, indeed, was obtained 

 in this way, that I found myself subjected to an unforeseen 

 source of failure. A number of the tubes failed, not by 

 explosion, but by the formation of a minute longitudinal 

 fissure at the breech, through which the borax and carbonic 

 acid escaped. I saw that this arose from the expansion of 

 the borax when in a liquid state, as happened with the fusi- 

 ble metal in the experiments with iron barrels ; for the cre- 

 vice here formed indicated the exertion of some force acting 

 verv powerfully, and to a very small distance. Accordingly, 

 this source of failure was remedied by the introduction of 

 a very small air tube. This, however, was used only in a 

 few experiments. 



In the course of the years 1801, 1S02, and 1803, I made 

 a number of experiments, by the various methods above de- 

 scribed, amounting, together with those made in gun-bar- 

 rels, to one hundred and fifty-six. In an operation so new, 

 and in which the apparatus was strained to the utmost of 

 its power, constant success could not be expected; and, in 

 fact, many experiments failed, wholly or partially. The re- 

 sults, however, upon the whole, were satisfactory, since 

 they seemed to establish some of the essential points of this, 

 inquiry. 



These experiments prove, that, by mechanical constraint, 

 the carbonate of lime can be made to undergo strong heat 

 without calcination, and to retain almost the whole of its 

 carbonic acid, which, in an open lire, at the same tempe- 

 rature, would have been entirely driven off; and that, in 

 these circumstances, heat produces some of the identical 

 effects ascribed to it in the Huttf)nian theory. 



By this joint action of heat and pressure, the carbonate of 

 lime, which had been introduced in the state of the finest 

 powder, is agglutinated into a firm mass, possessing a degree 

 of hardness, compactness, and specific gravity*, nearly ap- 

 proaching to these qualities in a sound limestone; and some 

 oi" the results, by their saline fracture, by their semi-trans- 



* £ee Appciidii— (to be given in a future Ilumbcr.) 



parency. 



