CHEMICAL News)
Nov. 25, 1881.

Reversal of the Spectrum of Cyanogen.
which show the reversal of the violet and ultra-violet
bands of this spectrum ; and the fa is perhaps of sufficient
nterest, especially in connexion with the question of the
vccurrence of these bands amongst the Fraunhofer lines,
to warrant the publication of this note. We have not yet
succeeded in determining precisely the conditions under
which tne reversal can be produced at will The most
complete reversals of these bands were obtained by the
use of the arc of a Siemens’ machine, in a crucible of
magnesia, fed with a considerable quantity of cyanide of
atznium. The photographs in this case show a very coms
plete reversal of the five bands near L, and of the two
stiong bands neai N, and a less complete reversal of the
six bands, beginning at about wave-length 4215. No
other metallic cyanides have given, when introduced into
the crucible, any such reversal; nor does a stream of
cyanogen, led in through a perforated carbon, produce the
effe®. Various other nitrogenous compounds have been
tried, but the only one which has given us anything like
the effet of the titanic cyanide is borate of ammonia.
Some photographs taken immediately after the introducion
 of borate of ammonia show distinély the reversal of
the group of bands near L. In one case when metallic
magnesium had been put into the crucible, the photograph
shows a reversal of only that art of the series which is
a :arest to the magnesium group, indicating that the reversal
 is due to the bright background supplied by the
sxpanded magnesium lines. There can be little doubt
that the greater stability of titanic cyanide and boron
sitride than of other nitrogenous compounds, has some
nfluence upon the result ; and the difficulty in producing
he reversal at will is in securing an absorbent stratum of
ufficiently high temperature and at the same time a suffi
:iently luminous background. The circumstances which
secure the former condition almost always produce in the
ac a still more intense radiation of just those rays which
are absorb-d, without that expansion of the lines which
shows out the absurption in the case of so many metallic
speira. The photographs are, however, conclusive
evidence that it is possible to secure both conditions.

THE CHEMICAL NEWS.
Vor. XLIV. No. 1148.

ON THE
ACTION OF THE OXIDES OF NITROGEN ON
GLASS AT A HIGH TEMPERATURE.
By THOS. M. MORGAN.

SEVERAL attempts were made to determine the nitrogen
in organic nitro-derivatives by heating the substance in
sealed tubes of hard glass containing oxygen, and in
presence also of a little mercury to effe@ the redudion of
any oxides of nitrogen which might be formed, but in all
cases the pitrogen obtained was considerably less than
the quantity theoretically present in the substance analysed.
The source of this deficiency was eventually traced to
the action which the oxides of nitrogen exerted on the
alkali of the glass, and also on the mercury. For when
some of the tubes which had been subjected to a temperature
 not above dull redness were washed with a little
water, the washings could always be shown to contain a
nitrate and a soluble salt of mercury ; cthers, the temperature
 of which had been higher, contained nitrates and
nitrites, but no soluble merzury salt.
For the purpose of showing mere conclusively that the
glass was thus attacked, and in order also to investigate
the extent of the action, the following experiment was
performed. A tube of hard glass, 50 c.c. capacity, was
cleaned until the evaporated washings left no appreciable
residue. A quantity of oxygen was next introduced, and
then 0 much nitric oxide that the tube was filled with
red fumes; after which it was heated to dull redness for
two hours. When cold it was still full of red fumes, and
when these were withdrawn it was washed as before, and
the evaporated washings left a residue of 0'0038 of a grm.,
consisting of nitrates and nitrites. The same experiment
was repeated three times on the same tube, the second
residue was 0'0044 of a grm., and the third o-0022.
Another tube gave 0:0048.
As might be expected, this aGion ismuch more energetic
at a high than at a low temperature, and it appears to be
very slight until the heat approaches redness. In the
analysis of such nitrogenous compounds as have the
nitrogen in combination with oxygen, a certain deficiency
of nitrogen, varying with the temperature employed. may
therefore be expected.
Viftoria College, Jersey,

ON MANGANESE NODULES AND
THEIR OCCURRENCE ON THE SEA-BOTTOM,*
By J. Y. BUCHANAN.

THE specimens exhibited consist of two nodules from the
South Pacific and of several from Loch Fyne in Scotland,
2» number of manganiferous worm tubes, and two samples
»f the mud in which these tubes and nodules are found
n Loch Fyne. I have, besides, some very curious specinens
 of cobalt nodules from New Caledonia, which I owe
to the kindness of my friend Prof, Liversidge, of the
University of Sydney. These Lave recently come into my
sands only within the last few days, and I exhibit them as
curiosities which may have an interest for some of the
members present,
My method of dredging for mud consists in anchoring
:he vessel by a dredge in the form of a Trotman’s anchor,
which carries a frame instead of a bar, connecting the
Jukes. To this frame is laced a bag, which receives the
mud which would otherwise drop off theanchor on heaving
up. This method has proved successful in two ways,
First, by keeping the vessel stationary, while the anchor
is down, and so admitting of temperature observations
being made, and water samples being colle®ed without
having to resort to troublesome manceuvres, and second,
by bringing up a large specimen of the mud taken, not
from the soft surface layer, as is the case with the flat
dredge, but from the underlying and stiffer material.
My first and best haul of manganese nodules, however,
was brought up on an ordinary kedge anchor and adhering

NOTE ON THE REVERSAL OF THE
SPECTRUM OF CYANOGEN *
By G. D. LIVEING, M.A, F.R.S., Professor of Chemistry, and
J. DEWAR, M.A, F.R.S., Jacksonian Professor,
University of Cambridge.

IN the course of many observations on the reversal of lines
of metallic spectra, we have frequently noticed dark shaded
bands which appeared to be the reversals of bands ascribed
to the oxides or chlorides of sundry metals ; more particularly
 we have seen them when experimenting with compounds
 of the alkaline earths, and we have repeatedly obtained
 a reversal of the green magnesium-hydrogen series;
but, until recently, we have never seen any reversal of
the shaded bands of the speétrum of cyanogen, though
our attention has been constantly directed to this spectrum.
Quite lately, however, we have obtained photographs

* Read before the Roval Society, November 17, 1881.

* Read before the British Association, York Meeting, Se@ion B.