The quantity of ammoniac in a solution of specific gravity not in the table, may be thus determined—find the difference between the two specific gravities nearest to it in the table; d, and the difference between their quantities of alkali, b; likewise the difference between the given specific gravity and that nearest to it, c.
then
d : b :: c : x
and
| bc | |
| x = | —— |
| d |
Which, added to the quantity of the lower specific gravity, is the alkali sought.
The differences in specific gravity of the solutions of ammoniac at temperatures between 4O° and 65°[70] are so trifling as to be hardly ascertainable, by our imperfect instruments, and consequently are unworthy of notice.
It is possible at very low temperatures to obtain ammoniacal solutions of less specific gravity than,9, but they are incapable of being kept for any length of time under the common pressure of the atmosphere.
IV. Combinations of Ammoniac with Nitric Acid,
Composition of Nitrate of Ammoniac, &c.
200 grains of ammoniacal solution, of specific gravity,9056, were saturated by 385,5 grains of nitric acid, of specific gravity 1,306. The combination was effected in a long phial, the nitrous acid added very slowly, and the phial closed after every addition, to prevent any evaporation in consequence of the great increase of temperature.[71] The specific gravity of the solution, when reduced to the common temperature, was 1,15. Evaporated at a heat of 212°,[72] it gave 254 grains of salt of fibrous crystalization. This salt was dissolved in 331 grains of water; the specific gravity of the solution was 1,148 nearly.