244 



HYDROGENATED COMPOUNDS OF NITROGEN. 



the temperature of the salt melted is raised by some source of 

 heat, without, however, the temperature being arrested at any 

 fixed point between 200 and 300. Pure nitrogen monoxide is 

 thus given off. 



But if we go on raising the temperature, the reaction becomes 

 explosive at the time that the multiple products appear that 

 are due to the many distinct modes of simultaneous decom- 

 position, such as are shown on p. 5 of this work. All these 

 phenomena are of the same order as those manifested generally 

 by exothermal reactions, and their variety is a characteristic of 

 explosive substances. 



3. However, according to the author's experiments on the 

 decomposition of ammonium nitrate, even with the greatest 

 care, the quantity of nitrogen monoxide 

 collected remains always considerably less 

 than the theoretical quantity. This is 

 on account of the volatility, real or ap- 

 parent, of the ammonium nitrate. The 

 difference is very great, even if we work 

 with the lowest possible temperature, and 

 in such a way as to prevent, as far as 

 possible, the portions sublimed in the 

 cold parts of the apparatus from gradually 

 falling into the heated parts at the same 

 time as the condensed water. 



4. We can, in fact, sublime ammonium 

 nitrate without destroying it to any 

 extent (Fig. 41) . by placing this salt, 

 previously melted, in a capsule, E, which 

 is closed by means of a sheet of blotting 

 paper fastened over the top and sur- 

 mounted by a cardboard cylinder, CC', 

 the latter being filled with large pieces of glass. This is heated 

 over a sand bath, S, by means of a Bunsen burner, B, properly 

 regulated, care being taken that the temperature of the melted 

 salt (which is shown by a thermometer, 0, plunged obliquely 

 into it) does not exceed 190 to 200. A very considerable 

 proportion of the salt is then sublimed in beautiful brilliant 

 crystals, adhering to the sides of the capsule and to the lower 

 surface of the paper. A portion of the salt even passes through, 

 and condenses above the capsule, in the form of a white smoke 

 very finely divided and very difficult to collect. 



At first, the existence of some special compound in this 

 smoke, such as nitric amide, was suspected; but its identity 

 with ammonium nitrate was proved by a complete analysis. 

 The temperature of the paper thus traversed by the vapour 

 may rise above 120 and even 130 degrees (as shown by a 

 horizontal thermometer, t, laid upon the upper surface of the 



Fig. 41. Sublimation of 

 ammonium nitrate. 



