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tions over an electroscope by means of a constant
current of air.
The following table shows the results of the
measurements obtained:
KAUIUM AND HOlill M I.N COAL.
THE COAL TRADE BULLETIN. 53
Radium Radium
(IO- 1 -gram.) (1 .-"'gram.)
^ .J sly OJ & O _
ri..,-_iv. . ai d d 73 S C d d
Ongin. « . jj« | g g S.
3|| §s| sa ^s »§ fe§
'cuS*- -^^v. H w """* ipn -^ tW *-~ l C|_|
>tnOj2~o.io do co do
.- < — KH M P-H l-P
Lievin 200 46 *0.5 *0.02
Anzin 2,000 3.5 *0.5 *0.01 *0.5 *0.01
Lens 500 11 S.8 0.97 3 0.33
Frankenholz.. 2,000 2 2 0.04 1.5 0.03
Mons 2,000 2.3 *0.5 *0.01 1.2 0.02
*Less than this amount.
It is thus evident that coal contains certain proportions
of radium and thorium. With regard
to the problem whether these proportions are able
to account for the enormous yields of helium mentioned
above, the following calculation, relating
to firedamp from the Frankenholz colliery, may be
given.
This mine emits a daily quantity of 10 cubic
metres of helium, and, assuming that it continues
to do so for 20 years, the total quantity of
helium given off into the atmosphere in that period
yvill be 73,000 cubic metres. Taking the radium
ancl thorium content as set forth in the table, and
in vieyv of the known layvs of the production of
helium and thorium, this coal will have produced
since the carboniferous period—that is to say,
during about 100 million years—2 cubic millimetres,
2.10-3 of helium per gramme ot coal, and
consequently the weight of the coal furnishing
the 73,000 cubic metres of helium would be 33
milliard tons, occupying a space of 22 milliard
cubic metres, or about 1,000 times the annual coal
output in France. It is, hoyvever, not improbable
that a large portion of the helium remains occluded
in the coal, and that only a small fraction is
liberated, so that the mass of coal rea'ly necessary
for the disengagement of 73,000 cubic metres of
helium in the mine in question would be very
much greater than 33 milliard tons -perhaps 100
times that figure. It would seem, therefore, that
only a small fraction of the helium in firedamp
originated in the radio-active constituents of the
c-oal.
On the other hand, it appears from the author's
researches that the helium in firedamp is
always accompanied by the other four rare gasesneon,
argon, crypton and xenon. Now these are
certainly not produced by the coal, and, since previous
experiments have shown that the five rare
gases are always found associated in firedamp, it
is evident that the radio-active substances in coal
play only a very small part in the production of
the helium in firedamp.
The problem may also be approched by taking
into consideration surrounding rocks, whieli also
contain radio-active substances. According to
the latest researches, the average radium content
in sedimentary rocks is 1.5 gramme, 5.10-12 per
gramme of rock, ancl that of thorium 1.16 gramme,
10-5 per gramme—that is to say, 49 times as much
as in coal.
However this may be, there is no doubt that
only a small portion of the helium in coal is of
recent formation, nearly the whole being fossil,
and there is also no doubt that most of the helium
has not originated in the radio-active substances
in the coal. The manner in yvhich this extraneous
helium has been introduced into the coal,
toegther with the other rare gases accompanying
the helium in firedamp, is under investigation.
MINE INSPECTORS PLAN
FOR ANNUAL CONVENTION.
At a meeting of mine inspectors held in Pittsburgh,
April 5, preliminary arrangements yvere
completed for the annual meeting of the Mine Inspectors'
Institute of America, which will be held
in Pittsburgh, commencing June 9. The technical
program is being worked out by a committee
and yvill be announced early in May.
The entertainment feature of the convention will
be in charge of the bituminous inspectors of this
district, I. J. Roby of Uniontown being chairman
of the entertainment committee. The guests on
tlie evening of the opening day of the convention
will be given a boat ride up the Monongahela
river as far as McKeesport, then back to Coraopolis.
A banquet will be arranged for the evening
of June 10. Technical entertainment will consist
of the demonstration at Bruceton and a visit
to the Linited States Bureau of Mines in this city.
Regular sessions of the institute will be closed
to outsiders. Some of the most notable men in
the engineering fields of the coal industry wili
address the institute, of yvhich David Roderick of
Hazelton, Pa., is president, and J. XV. Paul of the
United States Bureau of Mines of this city is secretary.
Officers of the Bituminous Mine Inspectors' association
of this district are: President, Thomas K.
Adams, Mercer, Pa.: vice president, I. J. Roby,
Uniontoyvn; secretary-treasurer, Thomas S. Lovvther,
Indiana, Pa.