The sun., 1900-12-30

,,o,, ,,sn.otion OF the formula Of their
c,mpounds with hydrogen. thus;
~ A-o-A n-N Sc
Ins,anoos Of penta-, heNa-. and even hept a.
yalency are not wanting.
KEY TO STRUCTURE or CHEMICAL COM
POUNDS.
This was the key TO unlock the structure
NJ chenical compounds: and Franklands
Vows inst stated, are still held by chem
i.ts The determination Of the Constitu-
ion of compounds chiefly those Of carbon.
occupied the attention OF chemists almost
,yclusivcly until 1880. Tho plan OF action
,s much the same as that OF mechanician
who wishes 10 initiate complicated
rechanism. He must first dissec it into
e,rours Of mechanical contrivances: these
are next constructed. and they are finally
tglt together into the complete machine.
In certain cases the atoms Of carbon are
arranged in chains" as. for example.
in pentyl alcohol,
H,C-C-C-C-C-O-H
Hs IL, Hs lie.
each atom being tetrad. and It's "affinities.-
or powers of combination saturated either
with hydrogen or with those Of neighbor-
ing atoms OF carbon; in others they are in
the form of a ring as In benzene. the for
mula Of which was first suggested by Ke-
kule. viz:
"sSss:S'
or In both, as In ethyl benzene.
~,sss-s-s-.
One or more atoms Of nitrogen. or Of oxy-
pyridine.
.eEE;;,e- and furturane. III
and so on. Dy means OF conceptions such
as these many interesting compounds
have been built up out Of the elements
which they contain; e. s. urea and uric
acid, constituents Of urine; theobromine
and caffeine. tho essential principles Of
cocoa and tea: alizarine and indigo. vnlua-
be dye stuffs, and several OF the aka
loias. bitter principles contained in plants.
Of great medicinal value.
THE EFFEcr ON INDUSTRIAL PROGRESS.
They have led. too. to tho discovery OF
many brilliant colors. now almost uni
versally employed. to the exclusion Of
those less brilliant. because less pure.
yla pta In fxvn
cases from animals: the manufacture OF
e,,ncotton. dynamite and similar high
explosives; and to the development Of
the candle industry. the sugar manufacture.
20 Improvement in tanning. in brewing
and In the preparation OF gas and oils for
Illuminating purposes. In short. It may
he said that the industrial progress Of the
latter half OF the century has teen due 10
the theoretical views Of which a short
sketch has Just been given.
Such formula however, can evidently
not represent the true constitution OF mat
ter. inasmuch as the atoms are imagined TO
Ia on a plane, whereas II Is evident tina t
they must occupy space Of three dimensions
and possess the attributes Of soidity. The
conception which led to the formulation
n
Fhs later years director Of the institute
known by his name at Paris. and more
directly to LeBel bulletin de Ia Soclets
Chimique de Paris. 1870 and Want Hoff
voorstel tot Uitbreiding der Structuur-Fo
mules In de Ruimte. 1870. now profess
sor at Berlin. independently Of each other.
In is4s Pasteur discovered that 1t was pos
sible to separate the two varieties Of tar
taric acid from each other. and that that
one which rotated the plane Of polarized
ght to the right gave crystals with an
extra face. unsymmetricauy disposed with
regard to the other faces Of the crystal. The
variety. the solution OF which in water
was capable Of producing left-handed
rotation. also possessed a similar face. but
So placed that Its reflection in a mirror
reproduced the right-handed variety.
PHsteur also showed that mixture Of these
acids gave crystals not characterized by
On unsymmetrically placed face: and also
that the solution was without action on
nolarized light. These observations re-
mained unexplained until LeBel and
Tan't HofY. IN 1874. simultaneously and In
dcpendenly devised theory which has.
UP till now. stood the test Of research.
Il Is briefly this: Imagine two regular
tetrahedra. or three-sided pyramids. stand
ing each on its triangular base. An idea
can best be got by a model. easily made
by laying on a table three lucifer matches
60 "a 10 form an equilateral triangle. and
erecting tripod with three other matches.
70 that each leg OF the tripod stands on
one corner 81 the triangle At the centre
OF such tetrahedron an atom OF carbon
= supposed to be placed. Marsh gas, cha.
"a supposed 10 have such a structure, each
corner, or solid angle OF the structure Cof
which there are fouD being occupied by
IN atom Of hydrogen. This represents
'He solid or s'ereochemicol formula Of
methane or marsh gas. Now, suppose
one of the atoms OF hydrogen In each Of
these structures TO be replaced by chlorine.
the group tOID. or any other monovalent
clement or group 1t Is evident that. II not
exactly similar lowing TO the replacement
not having been made at similar corners
IN EACH, the two structures can be made
similar by turning one Of them round