_a._ Into a solution of sulphite of potash, which had been made by
passing sulphureous acid gas from a mercurial airholder into caustic
potash dissolved in water, I introduced 17 grains of dry potash. The
whole evaporated at a low temperature, gave 143 grains of salt. This
salt was not _wholly_ composed of sulphite of potash and potash; it
contained as well, a minute quantity of carbonate, and sulphate of
potash, formed during the evaporation.[158]
[158] See the excellent memoir of Fourcroy and Vauquelin on the
sulphureous acid, and its combinations. Annales de Chimie, ii, 54. Or
Nicholson’s Phil. Journal, vol. i, pag. 313.
120 grains of it finely pulverised, and retaining the water of
crystalisation, were exposed to 15 cubic inches of nitrous gas, over
mercury. The nitrous gas diminished with great rapidity, and in three
hours a cubic inch and nine tenths only remained, which consisted of
nearly one third nitrous oxide, and two thirds nitrogene that had
pre-existed in the nitrous gas. The increase of weight of the salt
could not be determined, as some of it was lost by adhering to the
vessel in which the combination was effected, and to the mercury. It
presented no distinct series of crystalisations, even when examined
by the magnifier; rendered green vegetable blues, and its taste was
very different from that of the remaining quantity of salt that had
been exposed to the atmosphere. A portion of it strongly heated over
mercury, gave out gas with great rapidity, which had all the properties
of the purest nitrous oxide.
When water was poured upon some of it, no gas was given out, and the
whole was equably and gradually dissolved. Alcohol, as well as ether,
appeared incapable of dissolving any part of it.
When muriatic acid was introduced into it, confined by mercury, a rapid
effervescence took place. Part of the gas disengaged was sulphureous
acid, and carbonic acid; the remainder was nitrous oxide.
_b._ I made a number of experiments upon salts procured in the manner
I have just described, with a view to obtain the compound of nitrous
oxide and potash, free from admixture of other salts.
When the mixed salt was boiled in alcohol or ether, no part of it
appeared to be dissolved. Finding that little or no gas was given out
during the ebullition of concentrated solutions of the mixed salts,
I attempted to separate the sulphate, sulphite, and carbonate of
potash, from the combination of nitrous oxide and potash, by successive
evaporations and crystalisations. But though in this way it was nearly
freed from sulphate of potash, yet the extreme and nearly equal
solubility of the other salts, prevented me from completely separating
them from each other.
By exposing, however, very finely pulverised sulphite of potash,
mingled with alkali, for a great length of time to nitrous gas, it was
almost wholly converted into sulphate; and after the separation of
this solution, evaporation, and crystalisation, at a low temperature,
I obtained the new combination, mingled with very little carbonate of
potash, and still less of sulphite.
The minute quantity of sulphite chiefly appeared in very small
crystals; distinct from the mass of salt, which possessed no regular
crystalisation, and was almost wholly composed of the new compound,
intimated mingled with a little carbonate. The new compound, as nearly
as I could estimate from the quantity of nitrous oxide absorbed,
consisted of about 3 alkali, to 1 of nitrous oxide, by weight.
It exhibited the following properties:
1. Its taste was caustic, and possessed of a pungency different from
either potash or carbonate of potash.
2. It rendered vegetable blues green, which might possibly depend upon
the carbonate of potash mixed with it.
3. Pulverised charcoal mingled with a few grains of it, and inflamed,
burnt with flight scintillations. Projected into zinc in a state of
fusion, a slight inflammation was produced.
4. When either sulphuric, muriatic, or nitric acid was introduced to
it under mercury, it gave out nitrous oxide, mingled with a little
carbonic acid.
5. Thrown into a solution of sulphurated hydrogene, gas was disengaged
from it, but in quantities too minute to be examined.
6. When carbonic acid was thrown into a solution of it in water, gas
was disengaged; on examination it proved to be nitrous oxide.
7. A concentrated solution of it kept in ebullition in a cylinder,
confined by mercury, gave out a few globules of gas, which were too
minute to be examined, and probably consisted of common air previously
contained in the water.
_c._ In the experiments made to ascertain these properties all the salt
was expended, otherwise I should have endeavoured to ascertain what
quantity of gas would have been liberated by heat from a given weight;
and likewise what would have been the effects of admixture of it with
oil. When some of the mixed salt was mingled with oil of turpentine,
part of it was dissolved, and the fluid became white; but no gas was
given out. On this coarse experiment, however, I cannot place much
dependance. If the combination of nitrous oxide and potash is capable
of combining with oil without decomposition, barytes and strontian[159]
will probably separate the oil from it, and thus it may possibly be
obtained in a state of purity.
[159] Unless the sum of affinity of the potash, oil, nitrous oxide, and
earths, should be inch as to enable the nitrous oxide to combine with
the earth, whilst the oil and alkali remained in combination, & c.
In a rough experiment made on the conversion of nitrous gas into
nitrous oxide, by concentrated solution of sulphite of potash with
excess of alkali, very little of the nitrous oxide was absorbed. Hence
it is probable that water lessens the affinity of potash for nascent
nitrous oxide.