The times., 1900-12-30

| tcoJ III combination Win eieCtrC-pOSttive
oxide Of potassium QS.O); while each Of
these proximate constituents of potas-
sium sulphate were themselves composed
OF the electromagnetic oxygen in combina-
ton with electro-positiye sulphur. or
potassium. On contrasting sulphur with
potassium however, the former was con-
sidered more electro negative than the
latter; SO that the group sOs as whole was
electromagnetic. while K.O was electro-posi-
tive. The symbols given above. which
are still In universal use, were also de-
vised by Berzelius for the purpose of Illus
trating and emphasizing his views. These
views, however, met with little acceptance
at the time in England.
Lavoisiers idea, that oxygen was the
necessary constituent of all acids, began
about this time to lose ground. For Davy
had proved the elementary nature of chlo-
rine; and hydrochloric acid, one of the
| strongest, was thus seen to contain no
| oxygen, and Davy expressed the view,
I founded on his observation, that iodic
acid" I.Os. was devoid of acid properties.
until dissolved in water, and that the
essential constituent of all acids was n.y.
drogen, not oxygen. The bearing of this
| theory on the duaiistic theory is that
while, e. g., sulphuric acid was regarded
| by Berzelius sOs. containing no hydro
! gen, and was supposed to be separated as
I such at the positive pole of a battery,
Davy's suggestion led to the opposite con-
I clusfon that the formula of sulphuric acid
Is HsSO+ and that, by the current. il is re-
solved into H. and S0.. Faraday's electro
lytic law, that when a current Is passed
through electrolytes in solution the ele-
ments are liberated in quantities proper
tional to their &c cuivalents led to the
abandonment of the dualistic theory. For
when current is passed in succession
through acidified water, fused lead chlo-
ride and a solution of potassium sulphate,
the quantities of hydrogen and oxygen
from the water, of lead and chlorin from
the lead chloride. and the potassium of the
sulphate are in accordance with Faraday's
law. But In addition to the potassium,
there is liberated at the same pole an
equivalent of hydrogen. Now, If Berze.
Illus theory be true, the products should
be SOs and E.O. but IL the opposite view
be correct. then Ks is liberated first and by
its subsequent action on water 1t yields
potash, and its equivalent of hydrogen.
This was pointed out first by Daniel, pro-
was regarded as a powerful argument
against Berzelius' system. In 1888, too,
Graham investigated the phosphoric acids,
and prepared the salts of three, to which
he gave the names ortho-, pyro-, and
meta-phosphoric acids. To understand
the bearing OF this on the doctrine of
dualism it must be remembered that PaO., |
pentoxide of phosphorus was at that date |
named phosphoric acid. When dissolved |
in water 1t reacts with bases, forming |
saltS-the phosphates. But the quantity |
of water necessary was not then consid- |
cred essential; Graham, however, showed I
that there exist three series of salts; I
one set derived from PyO,3Hso; one from !
P2Os-2hsO, and third from P.O5. HsO. His l
way Of stating the fact was that water |
could play the part OF !, bose; for example, !
the ordinary phosphate of commerce pos
sessed, according to him, the formula |
PsOs-2NasO. HsO; two thirds OF the water OF |
constitution" being replaced by oxide of |
sodium. Liebig, then professor at Giessen
(1S93-1SI3), founded on these and on similar
observations of his own the doctrine of ]
polybasic acids-acids in which one, two,
three, or more atoms of hydrogen were
replaceable by metals. Thus instead of
writing, as Graham did. P-0s. 2NaeO HsO, he
wrote PosNasH; and for orthophosphoric
acid POsHs. The group OF atoms POl
therefore existed throughout the whole se-
ries of carbohydrates, and could exist
in combination with hydrogen, with hy-
drogen and metals, or with metals alone.
Similarly the group (Paoz) was characteristic
OF pyrophosphates and (POJ of metaphos-
pilates. for PsOseHs s0PsO3H.; and P.Os H.O.
2POJH.
The first clear ideas of the structure of
the molecule were, however, gained from
the study of the compounds of carbon. 1t
was difficult to apply the dualistic theory
TO them, for few of them are electrolytes
and therefore their products of electro
lysis. being non-existent, could not be
classified. Nevertheless Gay-Lussac re-
garded alcohol, CHIC, as compound of CHI.
ethylene, and HsO. water. and oxalic acid tan-
hydrousl. Coz as one of co, with CO. The |
discovery of "isomeric compounds" 1. e..
of compounds which possess the same ul-
innate formula and yet differ entirely in
their properties. forced upon chemists the
necessity of attending to the structure of
the molecule; for only by such a supposi-
ton could the difference between two iso-
meric bodies be explained. In 1923 nebig
discovered that silver illuminate and sill.
yer cyanate both possessed the empirical
formula AgCNO; in 1926 this was followed
by the discovery by Faraday that oil gas
contains hydrocarbon Identical in COM
position with ethylene, CHI yet differing
from it in properties; and in 1920 Wohler,
professor in Gottingen QS00-1sS2). disccv-
cred that urea, a constituent of urine, |
could be produced by heating ammonium
cyanate. NHtCNO. = substance of the same |
formula. 1t therefore became clear that
the identity of compound must depend
on some other cause than it's ultimate
In 1893 Liebig and Wohier took an I'M
oortant step in elucidating this question
oy their investigations on benzoic acid
IN acid obtainable By distilling n resin I
named gum benzoin. They showed that ,
his acid. C7Hsos. coald be conceived as con- t
listing of the group CiIsO, 10 which they gave
he name 'benzoyl," in combination with l
)H; that benzoic aldehydo. C7aso might be $
egarded as its compound with hydrogen; I
hat i; also formed compounds with chIor. /
ne and bromine and sulphur, and re- /
placed hydrogen is ammonia CC7HsO. NH. I
they termed this group benzoyI, u COM Il
,ound element or a radical" This re- e
search was followed by one by Robert I
3unsen professor at Heidelberg, born in Y
S11, and recently $3.50 dead, which bore n
eference to cacodyl, compound of ar n
enic, carbon, and hydrogen, in which I
he idea of radical was confirmed and Il
mplihed. +
The idea of a radical having thus be- v