AMMONIA NITRATE WITH AMMONIA. 
365 
admixture, the closed flask containing the liquid was inverted, with its mouth below 
the surface of the required quantity of water, and maintained there by a wooden 
holder; the wire retaining the stopper was then cut, and the latter removed by 
means of a pair of tongs. The liquid rapidly descended into the water and was 
replaced by the latter, which in its turn was replaced by air, by bringing the 
mouth of the flask just above the surface of the liquids. These were then at once 
briskly stirred round with a thermometer, and the altered temperature noted, the 
entire operation of mixing having occupied but a very short time. A specific-gravity 
bottle was immediately afterwards filled with the mixture, so that no appreciable loss 
of ammonia could have been sustained, the more so that the experiments were made in 
winter. Lastly, its specific gravity was taken at the standard temperature and found to 
be 1043-8. By assuming that the water undergoes no change in density, the specific 
gravity of the liquid after its admixture with the water can be calculated, and proves 
to be 1258-6 instead of 1 191-6, its original specific gravity. 
When a solution of 12 parts of nitrate in 7 of water, which is an almost saturated 
one at 15°-5, is mixed with 5 times 12 or 60 parts of water, there is also a fall in tem- 
perature of 4°, accompanied by condensation * : for before admixture the specific 
gravity of the primary solution is 1298-7, while afterwards its specific gravity, 
calculated from that of the mixture, 1064-4, is 1336 ; whence it will be seen that the 
contraction in volume, though very considerable, is not so great as that experienced by 
the ammonia solution of the nitrate, as might indeed be anticipated from the fact that 
the calculated densities of the nitrate and the liquefied ammonia are both less than their 
densities in aqueous solution. 
When the liquid (No. 1 in the preceding Tables) containing the least proportion of 
nitrate, namely two thirds of its weight, was mixed with water in the proportion (for the 
sake of comparison) of five parts to one of the nitrate, the temperature was found to fall 
only about ^°. The admixture was effected as before, except that on removing the 
stopper the liquid was in this case violently expelled from the flask into the water by 
some ammonia becoming gaseous, and that then the water rose into the flask by absorbing 
this gas. The specific gravity of the mixture was found to be 1026-4, and from this 
was calculated that of the liquid after its admixture with water. Instead of its original 
specific gravity, which was 1072-5, it had in the mixture that of 1125-8. Compounds 
of the nitrate with ammonia in other proportions were also mixed with water, and 
results obtained confirming those just detailed. The proportion of five parts water to 
one of the nitrate was chosen for the comparative experiments in order to have the mixture 
dilute, and therefore less liable to lose ammonia by diffusion ; with less water a 
greater depression of temperature would no doubt have been observed, but the inves- 
tigation was not further pursued in this direction. 
The small extent of the fall in temperature when the liquid containing the least 
* Gay-Lussac first observed the fall in temperature with contraction in volume that occurs when a concen- 
trated solution of ammonia nitrate is diluted with water (Ann. Chim. Phys. i. p. 214). 
MDCCCLXXIII. 3 C 
