I 



10 MEMOIRONTHE 



thereon with a sledge. An explosion will ensue, with a very loud report. Of 

 course the operator's face should be protected by a mask, his hands and legs by a 

 leathern or woollen apron, and gloves. The operation may be performed by one 

 person, but more advantageously by two, as it is difficult for one to hold the iron 

 in the position most suitable for bringing the surfaces together with the requisite 

 degree of parallelism. 



13. In a letter in reply to one from Mr. Durant, of New York, respecting the 

 explosions which are the principal objects of these communications, I adverted to 

 the superiority of the affinity which exists between water and oxide of potassium 

 over that which exists between nitric acid and the same base,* as a reason why 

 the presence of the elements of water, or of hydrogen in union with carbon, 

 should, on ignition with nitre, give rise to explosive reaction. Obviously, the 

 consequence of the displacement of nitric acid by water must be, that the gase- 

 ous constituents of the acid, incapable of remaining in combination without a base, 

 would escape, either as nitrogen, nitric oxide, or oxygen gas, or, carbon being 

 present, partially, as carbonic oxide, or carbonic acid. 



14. Gum, sugar, starch, and lignin, consist of carbon in union with the elements 



* It may be well here to advert to the fact, that one of our young countrymen, Tilghman, has, without 

 any hint from me, not only perceived the property of water on which I have insisted, but likewise has 

 had the sagacity to suggest its application in various useful processes. These have all been founded on 

 that superior affinity of water for certain bases, on which, in my letter to Hayes, I had insisted as afford- 

 ing the rationale of the explosion of nitre either with this liquid, or with any substance containing its 

 elements. 



From the preceding suggestions, and some experiments, of which an account will be subjoined, it ap- 

 pears that the explosive violence of a mixture of nitre with substances containing carbon in union with 

 hydrogen, or with hydrogen and oxygen, so as to be competent to convert the base into a hydrate or 

 carbonate, is dependent on the force with whicii they may be held or brought together in a state of igni- 

 tion, being sufficient to permit of that increase of temperature which is necessary to explosive reaction. 



Probably at the temperature thus alluded to, the ingredients are all in a condition analogous to that of 

 a very dense explosive gaseous mixture. It is well known that such mixtures detonate with a velocity 

 apparently not less than that of an electrical discharge. A single electrical spark, a particle of plalina 

 sponge, even a sunbeam, may cause an explosion so instantaneous, that it is the collapse only that can be 

 observed. The dilatation which precedes the colla))se escapes scrutiny. However large the volume, 

 ignition in any one part seems to affect the whole at once. 



I infer, then, that when, nitre and certain compounds of carbon with hydrogen and oxygen, reach a 

 temperature at which the whole mixture, if not restrained mechanically, would take the aeriform state by 

 a sudden revolution in the electro-chemical polarities, that detonating combination ensues, to which, when 

 ignited, various gaseous mixtures are liable. A few cubic inches of olefiant gas, with twice the bulk of 

 oxygen, included in soap-bubbles and inflamed, will produce a report equal to that of a musket. The 

 accidental explosion of a half gallon of a similar mixture created a thundering noise like a field-piece, so 

 as to alarm the whole neighborhood within a furlong of my laboratory. 



Aware of the influence of confinement in augmenting the force of reaction between nitre and combusti- 

 bles, the distinguished chemists above mentioned (as having been called upon by the Corpojation of New 

 York to investigate the phenomena under consideration,) treated the absence of this condition as a reason 

 for discrediting the idea that the reaction of nitre with combustibles could account for them. But agree- 

 ably to the facts, I propose to show that there must have been a mechanical force in opeiation sufficient 

 to bring the matter into a state analogous to that which enables fulminating combinations, or explosive 

 mixtures of gas, to detonate either from ignition, from exposure to an electric spark, or, in some instances, 

 from a blow or catalysis ; in other words, from some influence like that exerci^ed by platina sponge. 



