<338 ACTION OF HEAT MODIFIED 



different metals*, produces a fubftance fo fufibiei as to melt 

 in tl)e heat of boiling-water. I conceived that great advantage, 

 both in point of accuracy and difpatch, might be gained in 

 theie experiments, by fubftituting this metal for the baked 

 clay above mentioned : That after introducing the carbonate 

 into the breech of the barrel, the fufible metal, in a liquid 

 ilate, might be poured in, fs as to fill the barrel to its brim : 

 Advantages of That when the metal had cooled and become folid, the breech 

 this method. might, as before, be introduced into a muffle, and expofed 

 to any required heat, while the muzzle was carefully kept cold. 

 In this manner, no part of the fufible metal being melted but 

 what lay at the breech, the reft, continuing in a folid ftate, 

 would effedually confine the carbonic acid : That after the ac- 

 tion of llrong heat had ceafed, and after all had been allowed 

 to cool completely, the fufible metal might be removed entire- 

 ly from the barrel, by means of a heat little above that of boil- 

 ing water, and far too low to occafion any decompofition of 

 the carbonate by calcination, though adling upon it in free- 

 dom ; and then, that the fubjed of experiment might, as be- 

 fore, be taken out of the barrel. 



This fcheme, with various modifications and additions, 

 Avhich pradice has fuggelled, forms the bafis of moft of the 

 following methods. 

 A ftrlkine phe- •'•" ^^^ ^'^^^ trial, a firlking phenomenon occurred, which 

 nomenon. When gave rife to the moft important of thefe modifications. Ha- 

 tha barrel was -^ ^„^^ ^ gun-barrel with the fufible metal, without any 

 completely filled & fe ' J 



■with fufible carbonate ; and having placed the bceech in a muffle, I was 

 metal only, a»d f^jrprifed to fee, as the heat approachecl to rednefs, the liquid 



theclofedend ^ ..... , , . , 



o» the iron ex- metal exudmg through the iron in mnumerable mmute drops, 

 pofed to heat in difperfed all round the barrel. As the heat advanced, this 

 greater expan- exudation increafed, till at laft the metal flowed out in 

 lionof the fluid continued ftreams, and the barrel was quite deftroyed. On 

 thrtexturlTf^^ feveral occafions of the fame kind, the fufible metal, being 

 the iron in very forced through , fome very minute aperture in Ihe barrel, 

 f "\T"^^ "^^"j fpouted from it to the diftance of feveral yards, depofiting 

 upon any fubftance oppofed to the ftream, a beautiful af- 

 femblage of fine wire, exadly in the form of wool. I imme- 

 diately underflood that the phenomenon was produced by the 

 fuperrcjr expanfion of the liquid over the folid mefal, in con- 



*■ Eight parts of bifmuth, five of lead, and three of tin. 



fequ€Hce 



