190 OXYGENATED COMPOUNDS OF NITROGEN. 



partial precipitation of barium hyponitrite. With ammonium 

 chloride there is produced a special decomposition, setting free 

 ammonia, which has already been observed by Divers. Accord- 

 ing to the above figures, we have, for potash and hyponitrous 

 acid at 14 



]ST 4 3 dilute + 2K 2 dilute liberates 2(+ 8'9 + 13'8 + 2'75 

 - 201) = + 2 x 5-35 Cal. 



Let us now compare these results with the analogous numbers 

 relating to the two other acids of nitrogen 



i(2HN0 3 dilute + Ag 2 0, forming 2AgN0 3 ) solid... + 10-7 Cal. 

 i(N 2 3 dilute + Ag 2 0, forming 2AgN0 2 ) solid ... + 12-1 

 }(N 4 8 dilute + 2 Ag 2 0, forming Ag 4 N 4 6 ) + 11-1 



These are nearly the same values as for silver oxide forming 

 solid salts. For potash, on the contrary, forming soluble salts 



i(2HN0 3 dilute + K 2 dilute) + 13-8 Cal. 



i(N 2 3 dilute + K 2 dilute) + 10'6 



i(N 4 3 dilute + 2K 2 dilute) + 5'4 



The relative weakness of the latter acids, a weakness which is 

 correlative with their decreasing percentage of oxygen, is here 

 more and more marked. 1 



8. STABILITY AND EECIPROCAL KEACTIONS OF THE OXYGEN 

 COMPOUNDS OF NITROGEN. 



1. The carrying out of so many thermal determinations has 

 led to the study of the formation and decomposition of the 

 various oxides of nitrogen, a subject which had not been re- 

 considered since the time of Gay-Lussac, 2 Dulong, 3 Dalton, 4 

 and Priestley. Some of Peligot's 5 famous experiments on 

 nitric peroxide and nitrogen trioxide have also been repeated. 



The results obtained were unexpected, and contrary to the 

 received opinions on the stability of nitric oxide. 



2. Nitrogen monoxide, according to Priestley, is decomposed at 



1 We think it well to give here the calculation of the heats of formation of 

 the hyponitrites according to the old formula. The calculation can only be 

 etfected upon the supposition that the oxidation by the bromine should not be 

 quite complete, 3*71 equivalents of oxygen having been fixed instead of 4, 

 which is equivalent to admitting that the action of the bromine should have 

 liberated + 30-65 Cal. per equivalent of silver (taking into account the 

 formation of AgBr, which is not changed). We thus find 



J(N, + 2 + AgBr = 2AgNO) - g-25 



N 2 + + water = N 2 dissolved - 22-90 



N 2 dissolved + Ag 2 = 2AgNG precip +11-15 



N 2 dissolved + K 2 = 2KNO dissolved ... + 5-35 



The deductions and general points of similarity remain moreover the same. 



2 " Annales de Chimie et de Physique," torn. i. p. 394. 1816. 



3 Ibid., torn. ii. p. 517. 1816. 



4 Ibid., torn. vii. p. 36. 1817. 



5 Ibid., 3 e serie, torn. ii. p. 58. 1841. 



