breaking. But if you break only >he tip of the small 

 end, the whole shatters into powder. This shattering is 

 attended with a loud report, and the povyder scatters alt 

 around. If the experiment be made in the air pump, 

 the drop bursts more impetuously, and the dust is finer 

 than when it bursts in the open air. This is a plain 

 matter of fact. I do not undertake to account for it. 



Gunpowder is commonly supposed to have been in- 

 vented by Barthold Schwartz, about the year' 1380. ^ 

 But Roger 'Bacon knew of it a hundred and fifty >ears^ 

 before Schwartz was bora. For in iris treatise de Nul- 

 litate Magica, published at Oxford in 121 (i, are these-' 

 words. "You may raise thunder and lightning at 

 pleasure, by only taking sulphur, nitre, and charcoal, 

 which single have no effect, but mixed together 1 and 

 confined in a cldse place, cause a noise and. explosioa 

 greater than that of a clap of thunder." 



The effect of gunpowder is owing to the spring of 

 fhe air, inclosed ia the grains and in the spaces between 

 them. All these springs arc dilated by the fire, and set 

 a playing at 6nce. The powder itself Only serves to' 

 light the fire, which puts the air in action. 

 , Aurum fulminans, a preparation- of gold, is far 

 stronger than gunpowder. A scruple of this acts more 

 forcibly than half a pound of that. A single grain laid 

 on a knife, and lighted at a candle, goes off with a 

 greater noise than a musket. 



30. Air is that ckar, transparent, compressible fluid, 

 which is extended at least round the terraqueous globe, 

 fceing with us about 46,656,000,000 times more dense 

 and sluggish than ether, betwixt which and the air there 

 is a very great affinity or attractive force, which is a* 

 their density ; i. e. the air contiguous to the ether takes 17 

 in and concentrates the ether proportionally to its 

 greater density, by which it is rendered more springy 

 and active, with this difference, that the air by contact 

 and cohesion in the parts of bodies, becomes solid and 

 unelastic (but ether never); from whence again, by heat, 

 fire, or dissolution of |u"ts being separated, its elasticity 



