Evening star., 1950-07-03
2 Hot Elements Made
In WeighobIe Amounts
Acc Piles Now Produce
Amerieium and Curium
By Thomus R. Henry

by InomoS H. nenfy
Production for the first time Of weigh
able amounts of the trans-uranic man
made elements americium and curium-
the hottest materials known--is an
nounced by the Atomic Energy Commits
sion.
Previously they have been produced
only In almost invisibly minute quarti-
ties in the University Of California cy-
clotron by bombardment of plutonium
with alpha particles. the nuclei Of helium
atoms.
Now, according to just declassified
report of Drs. A. Ghiorso. r. A. James,
L. o. Morgan and q. T. Seaborg Of the
California laboratory, it has been DEM
onstrated that forms Of both elements
can be produced more efficiently by
neutron bombardments in the great
uranium piles of the Acc.
Americium 24l is produced, it is an
nounced. in "milligram quantities" by
the neutron bombardment of form of
plutoniun, the synthetic element which
forms the basis for the atomic bomb.
BY continuing the bombardment con-
siderable part Of the americium In turn
can be transmitted into the constantly
glowing element curium.
The significance Of this accomplish
ment may be considerable. Up to now
new elements-as well as the still heavier
element berkelium- been scien-
tific curiosities of only theoretical
Importance. BY producing them in
weighable quantities 1t will be possible
for the first time to determine their
physical and chemical properties and
determine where they At into the pat
tern of the developing atomic age.
It also is quite likely, the California
workers say, that the neutron bombard-
ment process holds the promise of pro-
ducing heavier forms of these two ele-
ments with quite different properties.
It already is known that americium
exists In two forms, or isotopes. Pre-
stmably they have identical reactions
chemically. Both emit electrons, or beta
rays. But physically they differ pro-
foundly. The half-life of one is II hours.
The half-life Of the other, which has
been impossible to determine precisely.
is somewhere between 100 and 1000
years.
The Mississippi no longer can be con-
sidered the worlds longest river.
Measured from Lake Itaska in North
ern Minnesota, which generally is ac-
cepted as its ultimate source, the whole
river system Of the Father of Waters is
about 800 miles short of both the Anna
zon and the Nile. measured from their
ultimate sources.
This is the conclusion of the British
geographer, o. r. Walkey, in report
recently issued by the Royal Geographic
Society. It is based on laborious re-
examination Of the worlds five principal
river systems, based in part on United
States Air Force maps.
There are five gigantic river systems,
each more than 500 miles longer than
their nearest competitors, Mr.. Walkey
says. These are the Amazon, the Nile
Kagera, the Mississippi Missouri, the
Yangtze and the Yenisei-Selinga in
Mongolia and Siberia. Mr.. Walkey's
measurements included all intervening
lakes through which the tributaries Of
these rivers flow.
The source Of the Amazon is accepted
as Lake ViIlafro in the Andes from
which flows its chief tributary, the
Ucayah. The most accurate measure
ments now available give the length Of
the Amazon system as 1850 miles. A .
previously accepted figure has been
$3.50 miles.
The ultimate source of the Nile is con-
sidered Lake Victoria Nyanza through
the little Luvironza River. The length
Of the Nile system is 1920 miles-a de-
crease Of 10 miles from the most COM
mon previously accepted figure.
The entire Mississippi system is given
length Of 3.760 miles, the Yangtze
$500 and the Yenesei $3.50.
The Amazon basin also is credited
with being by far the largest in the
world. covering about 2.750 square miles.
This Is double the size of its nearest
competitor. the basin of the Congo which
is not itself among the worlds largest
rivers.