CO MPOUNDS OF NITROGEN WITH II V I > I :< H ; K N A N I > < >X YGEN 249 



gives its oxygen compound that is, oxide of nitrogen. The decompo- 

 sition of ammonia into hydrogen and nitrogen not only takes place at a 

 red heat and under the action of electric sparks, but also by means of 

 many oxidising substances ; for instance, by passing ammonia through 

 a tube containing red-hot copper oxide. The water thus formed may 

 be collected by substances absorbing it, and the quantity of nitrogen, 

 may be measured in a gaseous form, and thus the composition of 

 ammonia determined. In this manner it is very easy to prove that 

 ammonia contains 3 parts by weight of hydrogen to 14 parts by 

 weight of nitrogen ; and, by volume, 3 vols. of hydrogen and 1 vol. of 

 nitrogen form 2 vols. of ammonia. 1 1 



Ammonia is capable of combining with a number of substances, 

 forming, like water, substances of various degrees of stability. It is 

 more soluble than any other known gas, both in water and in many 

 aqueous solutions. We have already seen, in the first chapter, that 

 one volume of water, at the ordinary temperature, dissolves about 

 700 vols. of ammonia gas. The great solubility of ammonia enables it 

 to be always kept ready for use in the form of an aqueous solution 12 

 which is commercially known as spirits of hartshorn. Ammonia water 



owing to the combustion ceasing, but after a short interval this is, however, renewed, so 

 that one feeble explosion follows after another. During the period of oxidation without 

 explosion, white vapours of ammonium nitrite and red-brown vapours of oxides of nitrogen 

 make their appearance, while during the explosion there is complete combustion, and 

 consequently water and nitrogen are formed. 



11 This may be verified by their densities. Nitrogen is 14 times denser than hydro- 

 gen, and ammonia is 8 times. If 3 volumes of hydrogen with 1 volume of nitrogen gave 

 4 volumes of ammonia, then these 4 volumes would weigh 17 times more than 1 volume 

 of hydrogen ; consequently, 1 volume of ammonia would weigh 4 times heavier than the 

 same volume of hydrogen. But as these 4 volumes only give 2 volumes of ammonia, 

 therefore they weigh 8 times heavier than hydrogen, which we find to be actually the 

 case. 



12 Aqueous solutions of ammonia are lighter than water, and at 15, taking water at 

 4 = 10000, their specific gravity, as dependent on p, or the percentage amount (by 

 weight) of ammonia, is given by the expressions = 9992 42'5p 4- 0'21p 2 ; for instance, with 

 10 p.c. s = 9587. If the temperature be =t, but not less than 10 or above 20, then 

 the expression (15 t) (l'5 + 0'14_p) must be added to the formula for the specific gravity. 

 Solutions containing above 24 p.c. have not been sufficiently investigated in respect to 

 the variation of their specific gravity. It is, however, easy to obtain more concentrated 

 solutions, and at solutions approaching NH 3 ,H.,O (48'6 p.c. NH 3 ) in their composition, 

 and of sp. gr. 0'85, may be prepared. But such solutions give up the bulk of their 

 ammonia at the ordinary temperature, so that more than 24 p.c. NH S is rarely contained 

 in solution. Ammoniacal solutions containing a considerable amount of ammonia give 

 ice-like crystals at temperatures far below (for instance, an 8 p.c. solution at 14, the 

 strongest solutions at 48) which seem to contain ammonia. The whole of the ammonia 

 may be expelled from a solution by heating, even at a comparatively low temperature ; 

 therefore, in heating aqueous solutions containing ammonia a very strong solution of 

 ammonia is obtained in the distillate. Alcohol, ether, and many other liquids are also 

 capable of dissolving ammonia. Solutions of ammonia, when exposed to the atmosphere, 



