The evening times., 1900-05-30
SEARCH FOR A NEW ELEmEN1
Interesting Papers Read Before the
Royal Society in London.


At the meeting Of the Royal Society
yesterday two OF the papers read an
uounced results which would have been
thought incredible not so many years ego.
and indicate the singular delicacy az mod
ern methods of research in chemistry and
physics. Sir William CrOOkes told the tale
CT the hunting Of an element which very
possibly may prove 70 be new He has
not. indeed as yet so completely stripped
on its DISCUSSES as 20 Be able 10 pass il
round the room in q tube. but its final
capture has become only a question OF
time and Of a sufficient supply Of material.
The game was started in this way. , he
compounds OF comparatively rare metal
called uranium, used IN the arts 10 produce
certain green, yellow and black cOlOrs,
have been shown by NJ Henri BecquereI
10 emit rays capable Of affecting a sensitive
Photographic plate through a material
which is Opaque 10 ordinary light. Two
other substances, much more rare, called
)olCnlum and radiun, possess this prop
erty in a still greater degree, and some
had suggested that the apparent activity
Of the uranium compounds might really
be caused by small quantities Of these
metals.
Their discoverers. however. VI. and Nine.
Curie deemed this 20 be impossible, and
affirmed that the property OF emitting rays
which can act in the dark cn Photographic
plates belongs 10 uranium. and 10 another
rarity. called thOriUm. Sir ". CrCokes.
however did not feel satisfied that the
former material was the real cause Of this
strange result series or preliminary
experiments showed him that at any rate.
pitchbiende an oxide of uranium. from
which the metal is chiefly obtained for COM
mercial purposes, possesses this property
more than any other substance The cause,
therefore. would be found in pitchblende.
So active is this compound that a slab in
which il occurs in sIreaks au0ag mere
ordinary minerals, after being laid in
darkness upon a sensitive Photographic
plate for twenty-four hours. so much af-
fected il that when a print was taken
most OF the minerals were invisible. while
the streaks Of pitchblerde were quite
white. and even their edges seemed TO emit
a family luminous haze.
The next thing to determine was wheth-
er this singular action in any way de-
pended on the particular salt of uranium.
After a number of delicate experiments
Sir W Crookes found that rs u rule. this
was not the case-that an extremely pure
nitrate Of uranium had not the property
and could not be made to acquire il. The
effect. moreover. diminished as the purity
of the salt increased. Clearly. then. il
could not be due to the uranium. but to
some substance present in the compound
as an impurity. Now the hunt com
menced- There were three possibi tiles.
Two substances we're already knoNa to
occur in -polonium and -
dium-which also possessed the property
that has been attributed to uranium One
OF these might be the energetic substance.
Polonium was quickly dismissed: the IN
known substance was proved to be some
thing different from it. Radium presented
greater difficulties, for the unknown sub
stance agrees more nearly with il, though
probably it is not Identical
So the investigation rests for the pres
en-. 1t has been demonstrated that this ex-
traordinary emanation of rays, affecting
a sensitiZed plate, but very different from
ordinary light, is not a property of ura
mum at all. but OF some other substance
probably hitherto unrecognized. but pres
ent as an impurity. which possesses the
property to such an extent that quite
small quantities produce these striking
effects.
That in itself is a remarkable discovery
though the full significance appeals only
to experts. The other one. announced bv
Sir W. Roberts-Austen. though no more
than a remarkable advance on former
knowledge, will be more readily appreci
ated by amCteuTs. Some four years ago. in
his Bakerian Lecture he stated if gold be
placed underneath a column of lead and
the two be kept hot, though at a tempera-
ture well below that at which the latter
mineral melts, the gold diffuses itself in
the lead, so that even in twenty
four hours an appreciable quantity of the
former can be detected in the lower por-
tion Of the latter At that time he puts
aside similar cylinders OF the two metals
keeping them for four years at tempera-
ture OF about 7 65 degrees Fahrenheit.
At the end Of this period the gold
was found to have made its way into the
lead The quantity. as might be expected.
diminished with the distance from The
precious metal. 'whether gold can actually
evaporate in ordinary circumstances. as
Sir W Robsrts-Austen remarks, we do not