New-York tribune., 1921-11-07
Chemists Find Two
Kinds of Lead With
Different Weights
Study of Atomic Structure
Being Made at Harvard to
Determine Proportions of
Elements in Compounds

CAMBRIDGE, Mass, Nov 6.-The
atomic weights of nearly forty of the
ninety or more chemical elements out
OF which everything in the universe is
built have been definitely determined
by Harvard chemists in the course of
Investigations begun thirty-tive years
ago and extending up to the present
time.
Largely on account of his work in
this field of chemical research, Profess
sor Theodore w. Richards, SO. Nobel
prize winner in 1914 and director of the
" olcott Gibbs Memorial Laboratory at
harvard, has been appointed a member
of the international committee on ele-
ments, while Professor Gregory P. Bax-
ter, '96. formerly a pupil of Professor
richards and now an independent in
Nestlgator at Harvard has been chosen
Tor the international committee on
atomic weights.
The atomic weights of the elements
are described as the relative weights
IN which these elements combine with
each other to form the countless sub
stances of which the universe is con
structed. These weights have usually
been found to be amazingly constant.
Silver from AL parts OF the world and
from many different ores has always
the same atomic weight. Copper from
Europe is identical in this respect WIN
that mined under the bottom of Lake
Superior
Weights Are Inva@iable
Professor BaXter's work at Harvard
long since proved that the iron and
nickel which fall from the sky in me-
teorites coming from the spaces far
beyond the earth's orbis nave exactly
the same atomic weights as iron and
nickel from the earth, fact cited as
indicating, in one respect at least, the
unity of the universe.
The most important single result of
the Harvard study of atomic weights
is said to be the discovery, first proved
definitely some years ago by Professor
Richards and still holding good through
recent careful tests. that there exist at
least two kinds of lead instead OF one
1t was found that lead from radium
minerals, while it possesses properties
exactly similar to those Of ordinary
lead, has q smaller atomic weight, 206.l
as against 207.2.
The lead from radium minerals is
supposed to come from the decomposi-
tion Of radium. Why its atomic weight
is different from that of ordinary lead
whether ordinary lead may not iself
prove to be q mixture of lighter lead
with a heavier variety, perhaps due to
the disintegration of the element thori-
um, and whether other elements, hith-
erto supposed to be final and indivisi-
bic, may not t'also prove TO be mixtures
and thus open up a whole series of new
problems as to the composition of mat
ter, are open questions.
Chlorine Is a Mixture
Professor W. d. Harkins. of Chicago
has evidence that ordinary chlorine is
Il mixture, and F. W. Aston, of Cam
bridge, England. by an entirely differ
ent method, indicates that many other
elements are probably likewise COM
posed of atoms of different weights.
Harvard chemists arc working at
present to try to find out more about
these two kinds OF lead. but they are
hampered by the fact that, once mixed,
the two kinds cannot by any ordinary
chemical methods be separated.
Beginning with the study of the
atomic weights OF oxygen and hydro
gen, in which he assisted the late Pro
fessor Josiah Cooke, OF Harvard, Pro-
fessor Richards undertook q systematic
investigation OF atomic weights, being
inspired by an intense philosophic de-
sire to know more about the funda-
mental nature of matter.
In 1887 he published his figures for
copper, showing that the accepted
atomic weight OF copper was much too
low. He followed with barium and
strontiun. Since then he and Pro
fessor Baxter have determined the
atomic weights of calcium, magnesium.
zinc, nickel, cobalt, iron, meteoric iron
and nickel, uranium, casium, sodium.
potassium, chlorine. nitrogen. silver,
sulphur, carbon, lithium, lead, radio
active lead. aluminium, mercury, silicon,
boron. lanthanum, arsenic. bromine.
cadmium, chromium. iodine, manganese,
neodymium, praseodymium and phos-
uhorus