364 
DR. E. DIVERS OX THE UNION OF 
calculated specific gravity of the nitrate in dilute aqueous solution, namely 1758, accord- 
ing to Playfair and Joule. But the observations of Thomsen* show that the specific 
gravity of the nitrate appears to vary from about the number obtained by Playfair 
and Joule to that of 1565-5 at 18°, in a solution of 8 of nitrate in 9 of water; and I 
have myself found it to have in a solution of 12 nitrate in 7 water an apparent 
specific gravity of 1572-5 at 15°-5, a number not greatly exceeding that expressing its 
apparent density when liquefied by ammonia. The ammonia and the nitrate in the liquid 
have therefore each a less apparent density than they have when dissolved in water, 
and the nitrate a much less apparent density than its actual density in the solid state. 
7. The flask used for determining the specific gravity served also for some rough 
determinations of the expansivity by heat of the liquids of different composition. By 
observing the height of the liquid at 0°, and again at 15 0, 5, the expansion between these 
temperatures was ascertained, and from this the expansion between 0° and 100° calculated, 
on the assumption that the expansion proceeds uniformly. The results obtained were the 
following : — 
No. 
Ammonia nitrate. 
Ammonia. 
Expansion from 0° to 100° 
1. . 
. . . 1000 
495-5 
about -h 
2. . 
. . . 1000 
392-5 
1 
” 17- 
o 
O. 
. . . 1000 
385 
1 
” 17 + 
4. . 
. . . 1000 
334 
1 
” 17 + 
5. . 
. . . 1000 
316-5 
1 
” 18— 
They are sufficient to prove that the expansivity of the liquid increases with the ratio 
of the ammonia to the nitrate; they also show that the expansivity of ammonia 
liquefied in this way is similar to that of other liquids existing as such under the 
pressure of the atmosphere, and far less than that of ammonia and other substances kept 
in the liquid state only by great pressure. Thus, from the experiments of Andreeff f , 
it appears that ammonia liquefied by pressure expands nearly of its volume when its 
temperature is raised from 0° to only 20°. 
8. The volume of a mixture of the liquid with water is much less than the sum of 
the volumes of the liquid and the water used ; and yet the admixture is attended with 
a considerable absorption of heat. The same remarkable phenomenon is manifested 
when a concentrated aqueous solution of the nitrate is mixed with water, and, indeed, 
by concentrated aqueous solutions of other salts, though, I believe, not by any of them 
to the extent that it is by that of the nitrate in either water or liquefied ammonia. 
Person £ calls die heat that thus disappears the latent heat of dilution. 
When the liquid of specific gravity of 1191-65 (No. 6 in the preceding Tables), and 
composed of 1000 nitrate to 281-5 ammonia, was mixed with five times as much water 
as the weight of the nitrate in it, the admixture was attended with a fall of 4° C. in 
the liquids both at first at the temperature of the laboratory. In effecting the 
* Pogg. Ann. exlii. p. 337. f Ann. Chim. Phys. [3] lvi. p. 317. 
t Ann. Chim. Phys. [3] xxxiii. p. 448. 
