_a._ Phosphorus introduced into pure nitrous oxide at common
temperatures, is not at all luminous. It is capable of being fused,
and even sublimed in it, without undergoing acidification, and without
effecting any alteration in its composition.
About 2 grains of phosphorus were fused, and gradually sublimed, in 2
cubic inches of pure nitrous oxide, over mercury, by the heat of a
burning lens. No alteration was produced in the volume of gas, and a
portion of it absorbed by water, left a residuum of one twelfth only.
Phosphorus was sublimed in pure nitrous oxide over mercury, in a
dark room, by an iron heated _nearly_ to ignition; but no luminous
appearance was perceptible, nor was any gas decomposed.
_b._ Phosphorus decomposes nitrous oxide at the temperature of
ignition, with greater or less rapidity, according to the degree of
heat. We have already seen, that when phosphorus in active inflammation
is introduced into nitrous oxide, it burns with intensely vivid light.
Phosphorus was sublimed by a heated wire in a jar filled with nitrous
oxide, standing over warm mercury. In this state of sublimation an iron
heated dull red was introduced to it by being rapidly passed through
the mercury; a light blue flame surrounded the wire, and disappeared as
soon as it ceased to be red.
To phosphorus sublimed as before, in nitrous oxide, over warm mercury,
a thick wire ignited to whiteness was introduced; a terrible detonation
took place, and the jar was shattered in pieces.
By employing thick conical jars,[172] containing only a small quantity
of nitrous oxide, I effected the detonation several times with safety;
but on account of the great expansion of the elastic products, the jar
was generally either raised from the mercury, or portions of gas were
thrown out of it. Hence I was unable to ascertain the exact changes
produced by this mode of decomposition.
[172] Experiments on the detonation of nitrous oxide with phosphorus
in this way require great attention. The detonating jar should be very
conical; the nitrous oxide employed should never equal more than one
eighth of the capacity of the jar. The wire for the inflammation must
be very thick, and curved so as to be easily introduced into the jar.
When ignited, it must be instantaneously passed through the heated
mercury into the jar.
Perhaps the electric spark might be advantageously applied for
detonating phosphoric vapor with nitrous oxide.
_c._ As my first attempts to ascertain the constitution of nitrous
oxide were made on its decomposition by phosphorus, I employed many
different modes of partially igniting this substance in it over
mercury, so as to produce a combustion without explosion.
The first method adopted was inflammation by means of oxygenated
muriate of potash. A small particle of oxygenated muriate of potash was
inserted into the phosphorus to be burnt. On the application of a wire,
moderately hot, to the point of insertion, the salt was decomposed by
the phosphorus, and sufficient fire generated and partially applied
by the slight explosion, to produce the combustion of the phosphorus,
without the previous sublimation of any part of it.
The second way employed was the ignition of a part of the phosphorus,
by means of the combustion of a small portion of tinder of cotton,[173]
or paper, in contact with it, by the burning glass.
[173] It will be seen hereafter that these bodies are easily inflamed
in nitrous oxide.
The third, and most successful mode, was by introducing into the
graduated jar containing the nitrous oxide, the phosphorus in a small
tube containing oxygene, so balanced as to swim on the surface of the
mercury, without communicating with the nitrous oxide. The phosphorus
was fired in the oxygene with an ignited iron wire, by which at the
moment of combustion, the tube containing it was raised into the
nitrous oxide, and thus the inflammation continued.
_d._ In different experiments, made with accuracy, I found that the
whole of a quantity of nitrous oxide was never decomposable by ignited
phosphorus; the combustion always stopped when the nitrous oxide
remaining was to the nitrogene evolved as about 1 to 5; likewise that
the volume of nitrogene produced was rather less than that of the
nitrous oxide decomposed, and that this deficiency arose from the
formation of nitrous acid by the intense ignition produced during the
process.
Of one experiment I shall give a detail.
Temperature being 48°, two cubic inches of pure nitrous oxide, which
had been generated over mercury, were introduced into a jar of the
capacity of 9 cubic inches, graduated to,1 cubic inches, and much
enlarged at the base. A grain of phosphorus was inserted into a small
vessel about one third of an inch long, and half an inch in diameter,
containing about 15 grain measures of very pure oxygene; this vessel,
which swam on the surface of the mercury, was carefully introduced
into the jar containing the nitrous oxide. The phosphorus was fired by
means of a heated wire, and before the oxygene was wholly consumed, the
vessel containing it elevated into the nitrous oxide. The combustion
was extremely vivid and rapid. After the atmospheric temperature was
restored, the gas was rendered opaque by dense white vapor. When this
had been precipitated, and the small vessel removed from the jar, the
gas filled a space nearly equal to 1.9 cubic inches. On introducing to
it a little solution of green muriate of iron, and prussiate of potash,
green prussiate of iron was produced: hence, evidently, nitrous acid
had been formed.
On the admission of pure water, an absorption of rather more than,3
took place.
The 16 measures remaining underwent no perceptible diminution with
nitrous gas; the taper plunged into them was instantly extinguished.
To ascertain if the phosphoric acid produced in the experiments made
under mercury did not in some measure prevent the decomposition of
the whole of the nitrous oxide by the phosphorus, I introduced into a
mixture of 5 nitrogene and 1 nitrous oxide, ignited phosphorus: but it
was immediately extinguished.[174]
The Dutch Chemists found that phosphorus might be fused in nitrous
oxide without being luminous. They assert that phosphorus in a state of
inflammation, introduced into this gas, was immediately extinguished;
though when taken out into the atmosphere, it again burnt of its own
accord.[175] It is difficult to account for their mistake.
[174] Phosphorus burnt feebly with a white flame in a mixture of 4
nitrogene and 1 nitrous oxide.
[175] Journal de Physique, xliii. 328.