CONDITIONS OF STABILITY OF HYDROXYLAMINE. 251 



this excess by means of a gas pipette, the gas separated contains 

 barely a few hundredths of a gas almost insoluble in water 

 (nitrogen or nitrogen monoxide), which shows that the decom- 

 position of the hydroxylamine is almost inappreciable under 

 these conditions. However, the gas so separated contains a few 

 hundredths of the vapour of hydroxylamine. We may prove 

 this by the following process. This gas is heated with a few 

 drops of water, which dissolve the vapour at the same time as 

 the ammonia ; the gas not dissolved is taken away by means of 

 a gas pipette, then we add to the water a large piece of potash 

 (with its surface previously damped, so as to eliminate the 

 gases adhering to it) ; under these conditions the hydroxylamine 

 which existed in the water, and consequently in the ammoniacal 

 gas which this water had dissolved, is immediately destroyed 

 with formation of nitrogen, which is really produced and which 

 may then easily be observed. 



Hydroxylamine may then be regarded, according to these 

 facts, as existing in a free state and in a liquid form, in the 

 testing apparatus, where it impregnates the ammonium chloride. 



Its vapour tension, as deduced from the preceding experi- 

 ments, would indicate a boiling point near that of water. 



But hydroxylamine so formed does not exist long in a state 

 of purity ; it is destroyed little by little, giving rise especially 

 to nitrogen monoxide and ammonia 



4KE 3 = T 2 4- 2NH 3 + 3H 2 0. 



At the end of forty-eight hours^ nearly two-thirds had under- 

 gone this transformation, as found by an exact analysis made of 

 the products derived from a known weight of the hydrochloride ; 

 about a seventh had in the same time changed into nitrogen and 

 ammonia. 



The fundamental reaction, which* in this case produces nitrogen 

 monoxide, gives off, according to calculation, -f- 48*4 Gal., a 

 result relating to the following conditions 



4NH 3 dilute = N 2 Q'gas -f 2NH 3 dilute -J- 3H 2 liquid. 



The real reaction, N"H 3 being supposed to be gaseous, and a 

 being the heat of solution of NH 3 0> gives- off 4- 39*6 a. 



We see that all these quantities are far below the heat given 

 off in the reaction, engendered by nitrogen, viz. + 57. This ex- 

 plains why this last reaction preponderates under the influence 

 of concentrated potash. 



13. From these facts it follows that hydroxylamine is only 

 stable in presence of acids, but its union with these agents 

 deprives it of part of its energy. This is, moreover, generally 

 the case in chemistry; a system is the more stable, all else 

 being equal, in proportion as the fraction of its energy which it 

 loses is greater (see p. 123). 



