HYDROXYLAMINE. 245 



paper) without the paper being affected to any considerable 

 extent. This experiment has some importance, as it shows that 

 ammonium nitrate may be volatilised as it is without being 

 at first resolved into ammonia and gaseous nitric acid 



NH 4 N0 3 = HN0 3 + NH 3 , 



which would afterwards re-combine, the mixture when dis- 

 sociated possessing all the energy of the simple components. 

 In fact, we cannot understand how the vapour of nitric acid 

 could be in contact with the paper, at a temperature which 

 necessarily ranges between 130 and 190, without oxidising it 

 or destroying it instantaneously. 



5. Ammonium nitrate, from the point of view of its volatility, 

 and on account of many considerations, may be regarded as a 

 typical explosive substance. In fact, pure nitroglycerin may 

 also be evaporated without decomposition. Picric acid itself 

 gives off very appreciable vapours, which sublime, and are 

 condensed without alteration when the substance is heated 

 with great care. 



4. THERMAL FORMATION OF HYDROXYLAMINE OR OXYAMMONIA. 



1. We know that hydroxylamine is a product of reduction 

 intermediate between hyponitrous acid and ammonia. It may be 

 formed in a number of oxidations. It was thought expedient 

 to determine its heat of formation, and this was done by 

 decomposing its hydrochloride by means of a saturated aqueous 

 solution of potash, very fine and very pure crystals of the salt 

 being employed. 



2. Hydroxylamine, exposed under these conditions, is im- 

 mediately resolved into nitrogen and ammonia, according to 

 M. Lossen's observations. 



After having ascertained that no other product was formed 

 (with the exception of a few hundred ths of nitrogen monoxide) 

 during the first moments of a sudden reaction, and that the 

 proportion of hydroxylamine thus destroyed at the ordinary 

 temperature and in a few minutes may amount to four-fifths of 

 its total weight, the reaction was reproduced in the calorimeter, 

 working with a known weight of hydrochloride, and collecting 

 the gases given off over the water in the calorimeter itself, 

 so as to measure them exactly. 



3. We will now describe the apparatus employed in the 

 experiments (Fig. 42). 



(1) At the bottom of a large tube, TT, closed at one end, is 

 placed a known weight of aqueous solution of potash, saturated 

 at the temperature of the experiment. 



(2) In this large tube is suspended above the potash a smaller 

 tube, tt, containing exactly one grm. of hydroxylamine hydro- 

 chloride. 



