The times., 1900-12-30


the remarkable properties of Laughing
! gas" or nitrous oxide. At the same time
/ he constructed a galvanic battery, and be-
! gan to perform experiments with it in at
/ tempting to decompose chemical com
| pounds by its means. In 1901 Davy was
appointed professor of chemistry at the
Royal Institution. a society or club which
had been founded a few years previously
| by Benjamin Thomson, Count Rumford
for the purpose of instructing and
/ amusing its members with recent dis
coveries in chemistry and natural
philosophy. In 1901 Davy applied his
galvanic battery to the decomposi-
ton of damp caustic potash and soda,
using platinum poles. He was awarded
by seeing globules of metal resembling
mercury in appearance, at the negative
pole; and he subsequently proved that
these globules. when burned reproduced
the alkali from which they had been de-
rived They also combined with "oxy-
muriatic acid" as chlorine discovered by
Scheele) was then termed, forming ordi-
nary salt, If sodium be employed, and the
analogous salt, "muriate of potash" IL
the allied methal potassium were subject
ed to combustion. By using mercury as
the negative pole, and passing a current
through strong solution of the chloride
of calcium, strontium or barium, Davy sue
ceeded in procuring mixtures with mer-
curry or 'emalgams" of their metals to
which he gave the names calcium, stron-
tium, and barium. Distillation removed
most of the mercury, and the metal was
left in Ctp pte nf ft.ar, mi;
ty. The alkali metals, potassium and So
dunn, were found to attack glass, liberat-
ing 1.-The basis of the silex," to which the
name silicon has since been given.
Thus nearly the last of the "earths'' had
been decomposed. 1t was proved that not
merely were the "calces" of iron, copper,
lead and other well-known metals COM
pounds of the respective metals with oxy-
gen, but Davy showed that lime and Its
allies, strontia and baryta, and even silica
or flint, were to be regarded as oxides of
elements of metallic appearance. To COM
plete our review of this part OF the SUBJ
ject, suffice it to say that aluminium, a
metal now produced on an Industrial scale,
was prepared for the first time in 1877 by
Wohler, professor of chemistry at Coffin
6Niii ny liie dCllOu u DVldSSluil On EuiO-
ride, and alunlina, the earthly basis OF
clay, was shown to be the oxide of the
metal aluminium. Indeed, the preparation
Of this metal in quantity is now carried
out at Schoffhausen-on-the-R Rhine, and at
the Falls of Foyers, in Scotland, by elec-
trolysis of the oxide dissolved in melted
cryolite, a mineral consisting of the huo-
rides of sodium and aluminium by
method differing only in scale from shat
by means of which Dayy isolated sodium
and potassium in 1906.
To Davy too, belongs the merit of hav-
ing dethroned oxygen from its central po.
sition among the elements. Lavoisier
gave to this important gas the name "oxy-
gen." because he imagined it TO be the
constituent of all acids. He renamed the
common compounds OF oxygen in such a
manner that the term oxygen was not
even represented in the name-only in
ferred. Thus n nitrate is q compound
of an oxide OF nitrogen and an oxide of
metal; a "sulphate," of the oxide of a
metal with one of the oxides of sulphur,
and so on. Dayy, by discovering the ele.
mentary nature of chlorine, showed first
that it Is not an oxide of hydrochloric acid
(or muriatic acid, as 1t was then called;
and second. that the latter acid is the COM
pound Of the element chlorine with hydro.
gen. This he did by passing chlorine over
white-hot carbon-a substance eminently
suited TO deprive oxy-compounds of their
oxygen-and proving that no oxide of car.
bon is thereby produced; by acting on Ger.
tain chlorldes, such as those of tin or
phosphorus with ammonia, and showing
that 10 oxide Of tin or phosphorus is
and, lastly, by decomposing "mu-
riauc acid gas gaseous hydrogen chlo-
ride with sodium, and showing that the
only product besides common salt is hydro.
gen. Instead, therefore, of the former
theory that chloride was a compound of
the unknown basis of oxy-muriatic acid
with oxygen and the oxide of a metal. he
the simpler and correct view
that a chloride is merely compound of
the element chlorine with metal. In 1913
he established the similar nature of
1ucrine, pointing out that on the analogy
Of the chlorides it was a fair deduction
that the fiuorides are compounds of an
element, fluorine. with
metals: and that hydrofiuoric acid is the
true analogue Of hydrochloric acid. The
truth of this forecast has been established
)f recent years by Henri Moissan, who iso.
lated gaseous fuorine by subjecting
mixture Of hydrofluoric acid and hydrogen
potassium fiuoride contained in a platinum
L tube to the action OF powerful electric
current. He has recently found that the
lube may be equally well constructed of
copper; and this may soon lead to the in.
1ustrial application of the process. The
of isolating fiuorine is due to Its
chemical energy; for there |
are few substances, elementary or com.
bound. which resist the action of this pale !
yellow. suffoeadng gas. In 1911 iodine.
separated by Courtois from the ashes of |
sea plants, was shown by Davy to be an |
element analogous TO chlorine Gay-Lus- |
sac subsequently investigated 1t and pre-. |
Jared many Of its compounds; and In 1926 |
he last Of these elements, bromine, was |
discovered in the mother liquor of sea salt |
Jy Ballard. The elements of this group |
lave been termed "halogens," or salt |
producers"
While Davy was pouring his researches |
nto the astonished ears of the scientific |
md dllettante world, John Dalton. a Man.
chester schoolmaster, conceived a theory |
which has proved of the utmost service
o the science OF chemistry and which bids |
air to ortlast our day. 1t had been no.
iced by Wenzel by Richter. by wollas-
on, and by Cavendish. toward the end of |
he last century, that the same compounds
contain the same constituents in the same
or, as the phrase runs, pos
iess constant composition" Wollaston,
indeed, had gone one step further and had
hown that when the vegetable acid. OK