I 



Effects of Heat nzodijied hy Compression. 14 T 



28° without decomposition, that it would cuter into fusion. 

 The sequel will show that this conjecture was not without 

 foundation. 



I shall now enter upon the description of those experi- 

 ments^ the result of which I had the honour to lay before 

 this society on the 30th of August last (1804) ; fully aware 

 how difficult it is, in giving; an account of above five hun- 

 dred experiments, all tending to one point, but differing 

 much from each other in various particulars, to steer be- 

 tween the opposite faults of prolixity and barrenness. My 

 object shall be to describe, as short! v as possible, all 

 the methods followed, so as to enable any chemist to repeat 

 the experiments ; and to dwell particularly on such cir- 

 cimistances only as seem to lead to conclusions of im- 

 portance. 



The result being already known, I consider the account I 

 am about to give of the execution of these experiments, as 

 addressed to those who take a particular interest in the pro- 

 gress of chemical operations : — in the eyes of such gentlemen 

 I trust that none of the details into which I must enter will 

 appear superfluous. 



II. Prlnciplt; of Execution itpon which the following Expe- 

 riments Here conducted. — Experiments iiith Gun-Barrels 

 filled with Hiked Clay, and welded at the Muzzle. — Me- 

 thod ivith the Fusible Metal. — Remarkable Effects of its 

 Expansion. — Necessity of introducing Air. — Results ob- 

 tained. 



When I first undertook to make experiments with heat 

 acting under compression, I employed myself in contriving 

 various devices of screws, of bolts, and of lids, so adjusted, 

 I hoped, as to confine all elastic substances ; and perhaps 

 some of them might have answered. But I laid aside all 

 such devices, in favour of one which occurred to me ia 

 January 1798 ; which, by its simplicity, was of easy appli- 

 cation in all Gates, and accomplished all that could be done 

 by any device, since it secured perfect strength and tight- 

 ness to the utmost that the vessels employed could bear, 

 Whether formed of metallic or earthy substance. The device 

 K 2 depends 



