The Prince George's enquirer and southern Maryland advertiser. (Upper Marlborough, Md.) 1882-1925, 1904-01-15
RAD1UMANDITs MYSTERIES

pardon me even if it is again told; for
it forms the first chapter in volume
of which many have still to be written.
M. Henri Becquerel, prompted by
hint from the celebrated mathemati-
clan, M. Poincare, discovered that the
compounds of uranium, a somewhat
rare metal, as we'll as the metal itself,
were capable of impressing a photo
graphic plate wrapped up in black
paper, or otherwise protected. from
light. 1t was also found that such
salts, placed near a charged electro
scope, discharged it, the gold leaves
falling together. An electroscope, it
may be explained, is metal box with
glass sides; through hole in the lid a
wire passes. The stopper which closes
the hole and supports the wire is made
of sulphur, or sealing wax, or some
other material which does not conduct
electricity. From the end of the wire
are suspended two pieces of gold leaf,
hanging down so as to be visible
through the glass sides Of the box.
Ifa piece of sealing wax is rubbed,
so as to excite it electrically, and if
the projecting end of the wire is touch
ed with the rubbed sealing wax,
small charge of electricity is given to
the wire, and through it to the gold
leaves, 80 that they rerel each other,
and fly apart, making d figure like an
inverted V. If the wire be touched
with the finger the electric charge is
conducted away through the body,
and the leaves swing back into their
original position.
This effect of discharging was found
to be produced when salt or mineral
containing uranium was placed inside
the box. Nine. Curie, Polish lady,
living in Paris, noticed that the rate
at which the gold leaves fell together
was more rapid with certain uranium
minerals (specimens of pitchblende)
than could be accounted for by the
uranium oxide in the mineral; she
therefore separated the mineral into
it's groups of constituents-uranium,
iron. lead, barium, bismutb, etc. for
the mineral contains all these and
many other elements), and tested each
group as to its power of discharge.
At first she thought that she had
traced the discharging power to the
bismuth group, and attributed it to an
element which she named "polonium,"
after her native country.
This discovery has been disproved,
but it appears that the amount of
polonium obtainable is exceedingly
small, and difficult to separate from
bismuth. Subsequently Nine. Curie
discovered another element of the
barium group, possessing enormous
powers of discharge, and to this ele-
ment, which occurs in relatively great
er amount, she gave the name ira
dium."
1t is an undoubted element in the
sense in which that term is generally
used; it's salts resemble closely those
Of bariam, and its spectrum has been
observed by M. Demarcay, Prof.
Runge, and Sir William Crookes. It's
atomic weight has been determined by
Mme. Curie as 225; the atomic weight
of uranium is the highest known-240;
and there is some evidence from its
spectrum that radium may have even
a higher atomic weight-over $50
and that the sample analyzed by Nine.
Curie may not have been quite free
from barium, Of which the atomic
weight is only l37.
While these researches were in pro-
gress NJ Curie and DR.. Schmidt dis
covered simultaneously that another
element, thorium, of which the atomic
weight is 232, also possesses the power
of discharging an electroscope, and,
moreover, that if air be led over salts
of thorium, the air acquires and re-
tains. for a short time discharging
power. -" #
FURTHER DISCOVERIES.
The subject was taken up by Prof.
Rutherford, Of Montreal, and by Mr..
Frederick Soddy, who then worked in
his laboratory; and they found that if
the "active" air were cooled by passing
it through tube cooled with liquid
air it lost its "activity,' the active
portion remaining in the cold tube.
On warming the tube the active por-
tion was carried forward, and with it
the discharging power. They also
found that similar "emanation," or
gas, was evolved from salts of radium,
possessing a much more permanent
discharging power. While the 'ema-