Clifton College Scientific Society. 39 



which it expels from or2;anic bodies, acts just like an element in 

 building up fresh compounds. However, these compounds that 

 have in them the radicle NO., (which are easily formed, and can 

 be produced by the action of nitric acid on a great many sub- 

 stances, as woody fibre, carbolic acid, glycerine, &c,), are as readily, 

 or more so, decomposed again ; and thus they constitute many 

 very important explosive bodies. What takes place in exploding 

 all these bodies is very similar, and is exactly like that which 

 takes place in the explosion of gunpowder. If a mixture of 

 nitre (or potassic nitrate), carbon, and sulphur, in certain pro- 

 portions is heated, struck, or if the adhesion of its atoms be 

 otherwise disturbed, the nitrogen and the oxygen of the mole- 

 cule, NO-,, which I spoke of before, suddenly fly apart ; the 

 oxygen being thus set at liberty, or being, as it is called, in a 

 nascent condition, immediately combines with and oxidises all the 

 other elements in the substance so disturbed, and forms with all 

 of them new gaseous products; these gases, carbonic acid from 

 the carbon burned, steam from the hydrogen, and free nitrogen, 

 also a gas, being thus instantaneously formed out of a substance 

 which the moment before was either liquid (as nitro-glycerine), 

 or solid (as gun-cotton), and occupied therefore a far less space, 

 now tend to occuj^y, and will occupy, however much they are 

 compressed or held back, an immensely greater volume : there 

 results, therefore, an explosion, produced by the concussion of the 

 pent-np and heated gases on the air around them. 



Some of these nitro-substitution products, as they are called, 

 are well known, as gun-cotton (nitrocellulose), and nitro-glycerine ; 

 others, not so well known as nitrogen compounds, are Picric acid, 

 which explodes on contact with ozone (as I learnt from Ogle's 

 excellent compilation on that active form of oxygen), and again, 

 fulminic acid, both of them not known in the acid form, but only 

 in the salts called fulminates, as fulminating silver and gold — two 

 very dangerous bodies — and fulminating mercury, not quite so 

 explosive, from which percussion-caps are manufactured. 



II. I said before that the halogen compounds with N (N CL, 

 NIo, NBrs) were very explosive, and I have here some iodide of 

 nitrogen, the least dangerous of the three, which shows well how 

 feebly and loosely nitrogen is united with these elements, for even 

 on mere percussion, or at any rate by a slight heat, it explodes 

 with great violence. {Experiment). 



2. Tlie reason why the iodide of nitrogen is the least dangerous 

 of the three, seems to be that, in this case, where nitrogen is in 

 union with a solid (iodine), the products of the decomposition 

 which results from exploding it, are for the most part solid, and 

 so do not expand to a much greater bulk ; while the products of 



