The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1907-02-15
RAoIum IN eARTH's CRUST.
Estimates of Its Thickness Based on
Study of New Element.
Oondon Telegraph

Divergencies of opinion between the
biologists and the physicians regarding
the thickness to be assigned to the sol
Id crust of the earth are of long stand
ing. Thanks to the late NJ. Curie and
Nine. Curie. the discoveries of radium.
and to the researches OF Professor j. j.
Thompson and Professor Rutherford,
the physicists are now armed with
weapon of research of which former
savants had no idea.
1t will be remembered that about
three years ago r. J. Strut, F. r. s,
son of Lord Rayleigh, detected radium
In the deposit left by the waters of the
not springs of Bath. Following up his
investigations. Mr.. Strut has for a
considerable time been engaged in an
estimation of the average amount Of
r9dium contained in the representative
rocks of the earth's exterior
He has gathered specimens of gran
lite from Cornwall and Rhodesia: bas
alt from the Giants causeway. Green
land and the Victoria falls; serpentine
from the Lizard: syenite rocks from
Norway and leucite from Monte Som
ma, Vesuvius. compelling each and all
of these to yield their secret. First of
all the several rock fragments were de-
composed by chemical agency and then
the radium present was determined
quantitatively by it's "emanatiOn."
This emanation, i'm consequence of its
slow decay Of activity, may be stored.
mixed with air i'm an ordinary gas
holder and its Photographic and cleo
trical action can be examined for sew
eral days or even weeks afterward,
quite apart from the radium from
which il was obtained
The presence of radium. whether
there be relatively much or little of
Ii. can easily be denoted in ali igneous
rocks. In general the GRANTEES hold
most and the basaltic rocks least.
Moreover, from its uniform distribution
the total quantity in each mile of the
earth's crust has been Professionally
calculated.
Mr.. Strut is of the opinion that not
more than one-thirtieth of the earth's
volume can consist of materials similar
to those encountered on its surface and
from various mathematical and phySi-
cal considerations he allows a depth of
forty-five miles for the rock crust Of
the globe, suggesting further that the
maximum temperature in the bottom of
the crust is somewhere in the neighbor-
hood of 800 degrees centigrade for
200 degrees FahrenheiD. fifteen
times the temperature of boiling water.
Phis is the melting point of iron. that
OF silver being 1000 degrees centigrade
and gold 1.250 degrees centigrade. But
il Is considerably below the melting
point IF platinum. which. according to
a recent determination by DR.. J. A
HarkeT. is LILO degrees centigrade.
The result with regard to the thick
ness of the earth's crust may be COM
pared with the conclusion arrived at by
Professor john Milne, f. r. s, the dis
tinguished seismologist, lately put for
ward in a Bakerian lecture Professor
Mines study of the speeds OF earth
quake tremors, propagated through the
globe, led him 90 think that at a depth
of thirty miles below the earth's sur
face a maximum depth is reached at
which there are materials having phys
ical properties similar to those on the
surface.
A still more curious outcome of this
investigation remains to be noticed
enc touching the condition Of the moon. I
Mr.. Strut thinks that the view of some |
astronomers, in particular that of w |
II. Pickering. that the moon is not /
dead" but still exhibits volcanic ac- |
ton. is on the whole a reasonable as |
He also thinks. what is GER
tainly surprising. that it's natural neat |
must be far greater than that OF the 1
earth.