166 OXYGENATED COMPOUNDS OF NITROGEN. 



Both reactions, in fact, are simultaneously developed, but 

 the volume of the nitrogen collected is much greater than 

 that which should be produced if the whole of the available 

 water were changed into ammonium nitrite. In the above 

 experiments it represented more than double the theoretical 

 quantity, which is easily explained by the simultaneous de- 

 composition of a portion of the nitrite. An analysis showed 

 that the products did not contain any sensible proportion of 

 nitrate. 



The following are various thermal data relative to ammonium 

 nitrite. NH 4 N0 2 (64 grms.) dry + 120 times its weight 

 of water at 12'5 absorbs in dissolving 475 Cal. The heat 

 liberated when dilute nitrous acid unites with ammonia may 

 be deduced from the heat liberated when ammonium sulphate is 

 precipitated by barium nitrite, N 2 3 dilute + NH 3 dilute + H 2 O 

 liberates -f 91. 



The heat liberated by its decomposition into nitrogen and 

 water, NH 4 N0 2 solid = N 2 4- 2H 2 liquid, amounts, according to 

 the formula, to -f 73 '2 ; the water being gaseous, we should 

 have + 54 Cal. 



5. Silver nitrite. By double decomposition with solutions of 

 different degrees of concentration N 2 3 dissolved, + Ag 2 O preci- 

 pitated = 2AgN0 2 dissolved, liberates -}- 3*36. N 2 3 dissolved* 

 4- Ag 2 precipitated = 2AgN0 2 crystallised, liberates + 121. 



The heat absorbed in the solution of an equivalent of silver 

 nitrite is equal to 874 Cal. 



It is worthy of remark that the thermal formation of solid 

 silver nitrite 4- 821 exceeds that of silver nitrate -f 10*9, both 

 formations being reckoned from the diluted base and acids : 

 while the formation of the alkaline nitrates, such as solid 

 barium nitrate, liberates + 18*6, and that of ammonium nitrate 

 calculated from the same components 4- 187, figures which are 

 on the contrary higher than the heat of formation of the corre- 

 sponding nitrites. In fact, the formation of solid barium nitrite 

 liberates only + 13 '4, and that of solid ammonium nitrite 

 + 13*8. 



These relations deserve some attention, for they tend to 

 connect the nitrites with the chlorides and halogen salts, in the 

 case of which the thermal formation of the salts of silver, 

 calculated in a similar manner, exceeds even that of the alkaline 

 salts. Such relations are in conformity with the known 

 analogies between the group (N0 2 ) which plays the part of 

 a radical compound in the nitrites, and the simple radical 

 halogens, such as chlorine and its congeners; in other words, 

 Ba(N0 2 ) 2 is here compared to BaCl 2 and AgN0 2 to AgCl. 



6. Formation of nitrogen trioxide. The preceding numbers 

 concerning barium nitrite being known, the heat liberated by 

 the transformation of nitric oxide into dilute nitrous acid, is 



