126 
DE. AXDEEWS AXD PEOFESSOE TAIT OX THE 
spark action is expansion, but on allowing the gas to stand, it gradually contracts, in 
consequence of the absorption of the hyponitric acid gas by the sulphuric acid in the 
siphon tube. It is impossible to determine the precise amount of the first expansion, 
as a certain amount of absorption occurs at the same time ; but, in one imperfect trial, 
the ratio between the expansion and the subsequent contraction was nearly that of 1 : 2. 
This corresponds to the conversion of 8 vols. of protoxide of nitrogen into 4 vols. of 
hyponitric acid gas and 6 vols. of nitrogen. The silent discharge appears to produce 
the same result as the spark, but as the action is slower, the absorption interferes with 
any attempt to determine accurately the primary expansion. 
Deutoxide of Nitrogen presents the interesting example of a compound gas, which, 
under the infiuence both of the spark and silent discharge, undergoes, like oxygen, a 
diminution of volume. This is independent of the subsequent absorption of the hypo- 
nitric acid formed. This gas is remarkable for the facility -srfth which it is decomposed 
by both forms of discharge. The passage of sparks for two minutes, thi'ough a tube 
containing about 5 cub. cent., produced a contraction of the gas to nine-tenths of its 
original volume, followed after some time by a contraction not quite double of the former, 
from the absorption of the hyponitric acid gas. On continuing to pass sparks till the 
decomposition was finished, and waiting till the hyponitric acid gas was completely 
absorbed, the residue amounted to a little more than one-fourth of the original gas. 
This residue consisted of a mixture of 11 vols. nitrogen and 1 vol. oxygen. It is erfdent 
that the final result is a little complicated, but there can be little doubt that the action 
of the spark is to convert 8 vols. of deutoxide of nitrogen into 4 vols. of hyponitric acid 
gas, and 2 vols. of nitrogen. This decomposition may be due to the immediate action 
of the discharge ; or the deutoxide of nitrogen may, in the fii’st instance, be resolved 
into equal volumes of nitrogen and oxygen, the latter combining as it is formed with 
undecomposed deutoxide. 
Carhonic Oxide has given results of great interest, the investigation of which has already 
occupied a considerable time, although it is not yet completed. The principal facts 
have, however, been already ascertained, and as they present some remarkable analogies 
to those already described in the case of oxygen, we shall briefly allude to them here, 
reserving the complete investigation for a future communication. 
The carbonic oxide was prepared by heating oxalic acid with an excess of sulphmic 
acid, and absorbing the carbonic acid by means of a strong solution of hydiute of potash. 
The gas, as it escaped from the end of the apparatus, did not produce the slightest 
turbidity in lime or baryta water, and was completely absorbed by an ammoniacal solu- 
tion of the subchloride of copper. 
On exposing this gas to the action of the silent discharge, a steady contraction took 
place, and the surface of the positive platina wme became covered with a continuous 
deposit of a bronze colour. After some time, a trace, but only a trace, of the same 
deposit appeared at the point of the negative wire. If, after a contraction of 60 
millims. or 60 millims. of the siphon tube had been obtained, a few electrical sparks 
