The times., 1900-12-30
~HE progress of the science


Il While at first mankind was con
tented to observe certain phenom
ena, and to utilize them for industrial pur
poses, if they We're found suitable, 'philos
ophers.'' as the thinking portion of oui
race loved to call themselves. have Away!
attempted to assign some explanation fol
observed facts, and 10 group them into sim
liars and dissimilars. 1t was for long imas-
ined following the doctrines of the Greeks
and of their predecessors, that all matter
consisted of four elements or principles
names which survive to this day in pop
ular language. These were FIRE ''air,
water and earth" 1t was not until
the seventeenth century that Boyle in his
"Sceptical Chymist'' d66D laid the founda.
tions of the modern science by pointing out
that ii was impossible to explain the exis-
tence of the fairly numerous chemical sub
stances known in his day, or the changes
which they can be made to undergo, by
means of the ancient Greek hypothesis re-
garding the constitution of matter. He
laid down the definition of the modern
meaning of the word element" he de-
clined to accept the current view that the
properties of matter could be modified by
earth, OF water; and he defined an element
the constituent of compound body.
The first problem, Then, to be solved, was
to determine which of the numerous forms
of matter were TO be regarded as elemen-
tary. and which are compound, or COM
posed of two or more elements in state
of combination; and to produce such COM
pounds by causing the appropriate ele-
ments to unite with each other.
One OF the first objects to excite curiosi-
ty and interest was the air which sur
rounds US, and in which we live and move
and have our icing. 1t was, however, en-
dowed with a semi-spiritual and scarcely
corporeal nature. in the ideas of our ances-
tors, for ii does not affect the senses Of
light, smell or taste, and though it can be
-elt, yet it eludes our grasp. The word
''gas," moreover, was not invented until
Van Helmont devised it to designate va
rious kinds of airs which he had OBJ
served. The important part which gases
play in the constitution of many chemical
compounds was accordingly overlooked;
and. indeed, it appeared to be almost as
striking feat of necromancy to produce
a quantity of a gas of great volume from
a small pinch of solid powder as for
Jim" of enormous stature but of delicate
texture TO issue from brass pot, as re-
lated in the Arabian Nights Entertain
ments.' Gradually, however, it came TO be
recognized, not merely that gases have
corporeal existence, but that they even
possess weight. This, though foreshad-
owed by Tortieilli, Jean Rey and others,
was first clearly proved by Black, profess
sor OF chemistry in Edinburgh, in 1852,
through his mastery researches, as car
bonic acid.
The ignorance of the material nature of
gases and of their weight lies at the bot
Tom of the phlogistic theory, theory de-
eised by Stahl about the year 1890, to ac-
count for the phenomena of combustion
and respiration and the recovery or re
duction'' Of metals from their "earths'' by
heating with charcoal or allied bodies.
According TO this inverted theory, a SUBJ
stance capable of burning was imagined to
contain more or less phlogiston, a princi-
pie which It parted with on burning, leav-
Ing an eai1h deprived Of phl5giston, or
"dephloSiI1cated,' behind If a metal.
fhis eartn when heated with substances
rich in phlogiston, such as coal, wood,
-four and similar bodies recovered the
phlogiston. which it had lost on burning,
and with the added phlogiston its metallic
character. Other substances, such as
PHOSPHORUS and sulphur, gave solids or
acid liquids, to which phlogiston was not
so easy to add; but even they could be re-
phlogisticated. On this hypothesis, it was
the earths, and such acid liquids as sui
phuric or phosphoric acids. which were
the elements; the metals and sulphur and
phosphorus were their compounds with
phlogiston.
The discovery of oxygen by Priestley
and by Scheele in 1774, and the explanation
of its functions by Lavoisier during the
following ten years, gave their true mean
ing to these phenomena. 1t was then rec
ognized that combustion was union with
oxygen; that an earth or "calx" was to
be regarded as the compound of metal
with oxygen; that when a metal becomes
tarnished. and converted into such an
earthy powder, it is being oxidized; that
this oxide, on ignition with charcoal or
carbon, or with compounds such as coal,
-four or wood, Of which carbon is a con-
stituent, gives up its oxygen to the car
bon, forming oxide OF carbon, caybonic
oxide on the one hand. or carbonic acid
on the other, while the metal is repro
dueed in fits ''reguline" or metallic condi-
tion, and that the true elements are
metals, carbon, sulphur phosphorus, and
similar bodies, and not the products of
their oxidation.
The discovery that air is IN the nlai. a
mixture of nitrogen, an inert gas, and
oxygen, an active one, together with a
small proportion of carbonic acid Cor.
as 1t is now termed, anhydride)-a discov-
cry perfected by Rutherford, Black, and
Cavendish-and that water is a compound
with oxygen Of hydrogen, previously
known as inflammabie air, by Cayendish
and by Watt, finally oyerthrew the theory
of phloeiston: but at the beginning of this
century it still fingered on, and was de-
Tended by Priestley until his death in
1904. Such. in brief. was the condition of
chemical thought IN the year 1900 Seheele
had died in 11S6, at the early age of forty.
four; Lavoisier was one Of the victims of
the French Revolution. having been gull
lotned in 1924 Cavendish had ceased to
work at chemical problems, and was de- |
voting his extraordinary abilities to physi- |
osl problems of the highest Importance,
while living the life cf an eccentric re. |
cluse, and Priestley, driven by religious |
persecution from England TO the more toll |
Grant shores Of America, was enjoying a |
peaceful old age. enlivencd by occasional |
incursions into the region of seetariau con- |
troversy.
The first striking discovery of our GEN. |
tury was that Of the compound nature of |
the alkalies and of the alkaline carths. |
THIS discovery was made by Hrnnhru