evil—she will have the Life, Letters, and
Labours of Miss Jane Ann Stamper left her as
a legacy by my will.

LIGHTING BY OXYGEN.

THE experiments in lighting by oxygen lately
made in the Place de I'Hôtel-de-Ville, Paris,
have attracted so much attention, and have been
considered so important, that a statement of
their nature may be opportune. The question,
in fact, is very complex, comprising, in addition
to its scientific bearings, the grand consideration
of economy.

Everybody knows that the ordinary gas for
lighting burns, like all other combustibles, by
combining with the oxygen which is one of the
constituents of atmospheric air. The brightness
of the light depends, at the same time, on the
solid particles contained in the gas, and on the
rapidity with which those particles are burnt
by contact with the oxygen.

When a candle or a gas-burner is lighted in
a room, the combustion is effected by means of
the oxygen in the air. The oxygen, diluted by
azote (another constituent of atmospheric air),
does not reach the flame with sufficient rapidity
and abundance to draw forth its greatest
amount of brightness. The phenomenon is
similar to that which occurs in a fireplace in
which the fire is burning slowly. If you put
on the blower, the flame becomes whiter and
the flame brightens up. The reason is that,
by causing a stronger draught of air, you
increase the rapidity of the combustion. In a
petroleum lamp the same effect is very apparent.
The dingy and sooty flame becomes
brilliantly white as soon as the fixing of the glass
in its place has determined a strong current of
air to set in.

The combustion of a flame in air takes place
under unfavourable conditions. The combustible
is not utilised to the full extent of which
it is capable. The remedy for this is to supply
the flame artificially with all the oxygen it
requires, instead of leaving it to extract laboriously
what it can from the atmosphere. On
this clear and simple principle is based the
fundamental idea of lighting by oxygen. To
manufacture oxygen; to put it within reach of a
combustible rich in solid matters, and so to
make it give out and render its greatest
illuminating power: such is the problem to be
solved.

The proceeding is so simple and so familiar
to chemists and natural philosophers, that it
has almost daily been put in practice in courses
of lectures and in laboratories, under one shape
or another. The burning of iron-wire in a jar
of oxygen is an old and familiar experiment.
If, instead of burning ordinary gas and oxygen
merely by their mutual contact, you insert a
piece of chalk, or lime, or magnesia into the
flame, the solid becomes heated and emits a
light of dazzling brightness. This is the
Drummond light, so called after its inventor, which,
before the employment of the electric light,
was used, and still frequently renders good
service, in heightening the splendour of scenic
effects in the principal theatres of London and
Paris. For some time past endeavours have
been made to utilize it for lighting purposes.
The attempts, therefore, made at the Hôtel-
de-Ville are far from being a novelty.

There exist at least twenty English patents
and fifteen French brevets for methods of
lighting by oxygen. So long back as 1834, an
able natural philosopher, M. Galy Cazalat,
experimented on the system in Paris. Similar
attempts were repeated in 1858, in the Bois de
Boulogne; in I860, in London; and again, in
1865, by Mr. Parker, who, by substituting
magnesia for chalk, considerably increased the
intensity of light; in spite of which, the new
mode of lighting was nowhere turned to serious
account, although the light, so easily obtained,
is extremely beautiful, and the object of general
admiration.

The cause of its not having been adopted for
public use was the high cost price of oxygen.
Oxygen, as the product of the laboratory,
obtained by decomposing bioxyde of manganese
at an elevated temperature, could not be offered
at mercantile prices. There could, therefore,
be no reasonable hope of applying the Drummond
light to every-day purposes. The
problem, in consequence, shifted its ground; the
essential point was to manufacture cheap
oxygen, and every effort was turned in that
direction. A distinguished chemist, M.
Boussingault, of the Academy of Sciences, opened
the way, by discovering a very ingenious mode
of production, but unfortunately too slow to be
turned to profitable account. He employs a
substance known in laboratories as the bioxyde
of barium; this, when heated, gives up a
portion of the oxygen of which it is formed,
and which it has the power of reabsorbing
when subjected to a current of air previously
heated to a proper temperature. To obtain
oxygen, it therefore suffices to extract it from
bioxyde of barium, and then to restore that
substance to its primitive state; and so on,
repeating the same operation. This mode of
practice has its inconveniences when carried out
on a large scale. M. Archereau afterwards
endeavoured to obtain the same results by the
decomposition of sulphuric acid.

Last year, a young chemist, M. Mallet,
pointed out a process analagous to M.
Boussingault's, which M. Dumas communicated to
the Academy in terms of praise. It consists in
heating the protochloride of copper in contact
with the air. This composite substance
absorbs oxygen, and is thereby transformed into
an oxychloride. The temperature is then
raised to four hundred degrees centigrade, and
the oxychloride returns to its former condition,
yielding up the oxygen. Thus, by means of a
single heating, the oxygen of the atmosphere is
transferred to a given mass of material, and
afterwards stored in a gasometer. By this
extremely ingenious method we can lay hands on