On (f ne,tu fulmnaling Mtrcury. 17^ 



Finding that the powder could \>t fired by flint apd ftee), without a difagreeablc noife, 

 a common gunpowder proof, capable of containing eleven grains of fine gunpowder, was 

 filled with it, and fired in the ufual way : the report was (harp, but not loud. The 

 perfon who held the inftrument in his hand felt no recoil ; but the explofion laid open the 

 upper part^of the barrel, nearly from the touch-hole to the muzzle, and ftruck off the 

 hand of the regilter, the furface of which was evenly indented, to the depth of 0,1 of an 

 inch, as if it had received the impreffion of a punch. 



The inftrument ufed in this experiment being familiarly known,_ it is therefore fcarcely 



neceflary to defcrlbe it j fuffice it to fay, that it was of brafs, mounted with a fprlng 



, regifter, the moveable hand of which clofed up the muzzle, to receive and graduate the 



violence of the explofion. The barrel was half an inch in caliber, and nearly half an inch 



thick, except where a fpring of the lock impaired half its thicknefs. 



SECTION V. 



A gun belonging to Mr. Keir, an ingenious artift of Camden-town, was next charged 

 with 17 grains of the mercurial powder, and a leaden bullet. A block of wood was placed 

 at about eight yards from the muzzle, to receive the ball, and the gun was fired by a fufe. 

 No recoil feemed to have taken place ; as the barrel was not moved from its pofition, 

 although it was in no ways confined. The report was feeble : the bullet, Mr. Keir con- 

 ceived, from the imprefllon made upon the wood, had been proje£ted with about half the 

 force it would have been by an ordinary charge, or 68 grains, of the beft gunpowder* 

 We therefore recharged the gun with 34 grains of the mercurial powder : and, as the 

 great ftrength of the piece removed any apprehenfion of danger, Mr. Keir fired it from his 

 fhoulder, aiming at the fame block of wood. The report was like the firft in Sedlion IV. 

 ftiarp, but not louder than might have been expedled from a charge of gunpowder. Fof- 

 tunately, Mr, Keir was not hurt, but the gun was burft in an extraordinary manner. The 

 breech was what is callpd a patent one, of the beft forged iron, confifting of a chamber 0,4 

 of an inch thick all round, and 0,4 of an inch in caliber ; it was torn open and flawed iri 

 many dire£lions, and the gold touch-hole driven out. The barrel, into which the breech 

 was fcrewed, was 0,5 of an inch thick ; it was fplit by a fingle crack three inches long, 

 but this did not appear to me to be the immediate effecSt of the explofion. I think the 

 fcrew of the breech, being fuddenly enlarged, afted as a wedge upon the barrel. The ball 

 miflied the block of wood, and ftruck againft a wall, which had already been the receptacle 

 * of fo many bullets, that we coiild not fatisfy ourfelves about the Imprefllon made by 

 this laft. 



S E C T I O N VI. 



As it was pretty plain that no gun could confine a quantity of the mercurial powder 

 fufficient to projeft a bullet, with a greater force than an ordinary charge of gunpowder, 

 I determined to try its comparative ftrength inanothejr way. 



I procured 

 3 



