212 Mr. E. Howard on a new fulminating Mercury. 



than that charged with the gunpowder, whilst the sand sur- 

 rounding it was least disturbed ; and likewise because the glass 

 globe withstood the explosion of 10 grains of the powder fixed 

 in its centre: a charge I have twice found sufficient to destroy 

 old pistol barrels, which were not injured by being fired when 

 full of the best gunpowder. It also appears, from the last expe- 

 riment, that 10 grains of the powder, produced by ignition four 

 cubical inches only of air; and it is not to be supposed that 

 the generation, however rapid, of four cubical inches of air, will 

 alone account for the described force; neither can it be accounted 

 for by the formation of a little water, which, as will hereafter 

 be shewn, happens at the same moment : the quantity formed 

 from 10 grains must be so trifling, that I cannot ascribe much 

 force to the expansion of its vapour. The sudden vaporization 

 of a part of the mercury, seems to me a principal cause of this 

 immense yet limited force; because its limitation may then be 

 explained, as it is well known that mercury easily parts with 

 caloric, and requires a temperature of 600 degrees of Fahrenheit, 

 to be maintained in the vaporous state. That the mercury is 

 really converted into vapour, by ignition of the powder, may be 

 inferred from the thin coat of divided quicksilver, which, after 

 the explosion in the glass globe, covered its interior surface; 

 and likewise from the quicksilver with which a tallow candle, 

 or a piece of gold, may be evenly coated, by being held at a 

 small distance from the inflamed powder. These facts certainly 

 render it more than probable, although they do not demonstrate, 

 that the mercury is volatilized ; because it is not unlikely that 

 many mercurial particles are mechanically impelled against the 

 surface of the glass, the gold, and the tallow. 



