150 Effects of Heat modified ly Compression. 



plans of execution, and with considerable addition to my 

 apparatus. 



In the course of my first trials, the following mode of 

 execution had occurred to me, which I now began to put iu 

 practice. It is well known to chemists that a certain com- 

 position of different metals* produces a substance so fusible 

 as to melt in the heat of boiling-water. I conceived that 

 great advantage, both in point of accuracy and dispatch, 

 might be gained in these experiments, by substituting this 

 metal for the baked clay above mentioned : that after intro- 

 ducing the carbonate into the breech of the barrel, the fusi- 

 ble metal, in a liquid state, might be poured in so as to fill 

 the barrel to its brim : that when the metal had cooled and 

 become solid, the breech might, as before, be introduced 

 into a muffle, and exposed to any required heat, while the 

 muzzle was carefully kept cold. In this manner, no part of 

 the fusible metal being melted but what lay at the breech, 

 the rest, continumg in a solid state, would effectually con- 

 fine the carbonic acid : that after the action of strong heat 

 had ceased, and after all had been allowed to cool com- 

 pletely, the fusible metal might be removed entirely from 

 the barrel, by means of a heat little above that of boiling- 

 water, and far too low to occasion any decomposition of the 

 carbonate by calcination, though acting upon it in freedom j 

 and then that the subject of experiment might as before be 

 taken out of the barrel. 



This scheme, with various modifications and additions 

 vi.'hich practice has suggested, forms the basis of most of the 

 following methods. 



In the first trial a striking phaenomenon occurred, which 

 gave rise to the most important of these modifications. 

 Having filled a gun-barrel with the fusible metal without 

 any carbonate, and having placed the breech in a muffle, I 

 was surprised to see, as the heat approached to redness, the 

 liquid metal exuding through the iron in innumerable mi- 

 nute drops dispersed all round the barrel. As the heat ad- 

 vanced this exudation increased, till at last the metal flowed 

 out in contim.ed streams, and the barrel was quite destroved. 



* T,ight parts of bismuth, five cf leid. and three of tin. 



On 



