530 Dr. R. Hare on the Eocplosiveness of Nitre. 



ladle, meanwhile evaporating much more slowly than if the 

 temperature were less. In any one of these instances an ex- 

 plosion would follow from a contact being coerced between 

 the heated surface and the liquid. When a hammer is em- 

 ployed as above described, mechanical force produces that 

 contact, which, in the explosive union of incandescent oxide 

 of potassium with water, is caused by intense chemical affinity. 



11. The explosion produced by Hayes, as above mentioned, 

 and that which took place in my laboratory, as well as the 

 explosive reaction of oxide of potassium with water, gave a 

 practical confirmation to the inference, that the meeting of 

 water with the base of incandescent nitre could cause tre- 

 mendous results. Subsequently, in the winter of 1845-46, I 

 found that when nitre, by the flame of a hydro-oxygen blow- 

 pipe supplied with atmospheric air and oxygen, is heated to 

 incandescence, and then quickly submerged in water previouly 

 situated beneath the containing ladle, a sharp explosion en- 

 sues. I found, nevertheless, that when thrown, under like 

 circumstances, upon molasses or sugar, the effects were those 

 of deflagration rather than explosion. Yet, latterly, I have 

 fallen upon contrivances, by which pulverized sugar and nitre 

 may be made to explode. The first expedient which suc- 

 ceeded, was that of pouring melted sugar upon the face of a 

 hammer, so as to make a disc of commensurate size. Such a 

 disc, if it should not adhere, is easily made to do so by slightly 

 moistening the face of the hammer. Some nitre was put into 

 a thin shallow platina capsule, situated over a small anvil, 

 near one of its edges, so that the bottom of the capsule might 

 be reached obliquely by a hydro-atmospheric blowpipe flame. 

 Under these circumstances, the nitre having been heated until 

 its potash began to be volatilized, was struck with the sugar- 

 faced hammer. A smart detonation was the consequence. 

 This experiment may fail sometimes from the blow not being 

 properly given; from the nitre not being sufficiently hot; or 

 the capsule being ill-situated. The explosion of fulminating 

 mercury by a hammer fails sometimes, from the blow not 

 being so given as to produce a due degree of parallelism be- 

 tween the surfaces. 



12. Another method of producing explosive reaction is as 

 follows : — Nitre and sugar being coarsely powdered, let discs 

 of paper about 3 inches in width be prepared. Place one of 

 the discs upon an anvil, and cover it with a stratum of sugar. 

 Then cover the sugar with a stratum of nitre, placing over 

 this another of the discs. Heat a flat iron bar, wider than 

 the discs, to a welding heat, and quickly withdrawing it from 

 the fire, and holding it above the paper, strike it down thereon 



