THE COLLIERY GUARDIAN

AND

JOURNAL OF THE COAL AND IRON TRADES.

Vol. CX.

FRIDAY, DECEMBER 10, 1915.

No. 2867.

Explosions in Mines Committee : Seventh Report.

EFFECTS OF INHALING DUSTS APPLICABLE FOR STONE-DUSTING IN MINES.

In presenting the report (prepared by Dr. J. S.
Haldane, M.D., F.R.S.) to the Home Secretary, Sir
Henry Cunynghame states that the committee had to
consider whether the scattering of considerable
quantities of fine dust in a mine might not prove
dangerous to the health of persons engaged in work
there, especially when such dust contained silica, the
dust of free silica having long been known to be more or
less dangerous. The First Report described a series of
experiments upon the matter, which Prof. Beattie, of
the Liverpool University, undertook at the invitation of
the Committee. These experiments appeared to show
that the dust of argillaceous shale was innocuous. At
the end of the Sixth Report it was stated that further
enquiry into the subject was desirable, and that Dr.
J. S. Haldane, F.R.S., had been asked to undertake it.

Dr. Haldane’s report fully confirms the conclusion of
Prof. Beattie. His investigation has shown that dust
of argillaceous shale such as is found interstratified in
the coal measures in most mines of the United Kingdom,
and is being extensively used for stone dusting, although
it contains silica, is not in the least likely to prove a
danger to health. On the other hand, he finds ground
for suspecting that flue dust, which is also being used
for the same purpose, may have injurious effects, and
he advises that its use should be discontinued. Fie
concludes with valuable suggestions as to the kinds of
material which may be used without detriment to health,
and as to means for limiting as much as possible the
inhalation of dust by the persons in the mine.

With reference to the recommendations contained in
the Sixth Report, the following letter has been received
by the Committee from Prof. H. B. Dixon :

The University, Manchester,

July 21, 1915.

Sir,—As I did not have an opportunity before
leaving England last year of discussing the final draft
of the Sixth Report of the Explosions in Mines Com-
mittee, I wish to say that there is one passage in that
report to which I take exception.

The Committee say :—

The 1 : 1 mixture of coal dust and incom-
bustible dust can, we believe, be regarded as proof
against ignition by the flame of the most violent
firedamp explosion, (p. 11.)

These words appear to me to bear <a meaning which
goes beyond the fact experimentally established; they
amount to an expression of opinion that no explosion
of firedamp, however violent, is capable of igniting a
1 : 1 mixture of coal and incombustible dust.

Before so definite a conclusion could be drawn, I
think more evidence is required on the violence which
might be set up in /an explosion of firedamp, either
mixed with air alone, or reinforced by untreated coal
dust—as it might be along a working face.

With this reservation, I agree entirely with my
colleagues in the precautions recommended in the
Report.

I have the honour to be, sir,
Your obedient servant,

Harold B. Dixon.

Dr. Haldane’s Report.

The experiments initiated Under Sir William
Garforth’s direction by the committee of the Mining
Association of Great Britain, and carried forward at
Eskmeals by the Explosions in Coal Mines Committee
until definite quantitative results were reached, have
shown that by the addition of a certain proportion of
inert dust, the coal dust, which is the inflammable agent
in all great colliery explosions, may be rendered non-
inflammable, and that a practical means of entirely
preventing these great disasters is thus available. It is
known, however, that certain kinds of chemically inert

dust produce, when breathed in large amounts, or over
long periods, very serious effects on the lungs of men.
Hence, it is necessary to ascertain that any variety of
dust used for preventing explosions introduces no new
danger owing to its being breathed in such amounts as
might be the case among men employed in coal mines.
In response to the Committee’s request, I beg to present
the following report on this subject.

It is necessary, in the first place, to point out that
the question involved is one that requires careful con-
sideration, since the effects produced by inhaling certain
varieties of inert dust are extremely serious. Fortu-
nately, these grave effects are practically unknown in
connection with coal mining; but in certain kinds of
metalliferous mining and other occupations they give
rise to dangers which entirely dwarf those which at
present arise from explosions in coal mines. Statistic-
ally, this aspect of the subject has recently been dealt
with somewhat fully in the Report of the Royal Com-
mission on Metalliferous Mines, and the evidence has
been reviewed which points without a shadow of doubt,
to the connection between the inhalation of certain kinds
of dust during mining work and the occurrence, usually
after many years of exposure to this dust, of phthisis
and other lung disease. One of the witnesses before the
Commission was Prof. Beattie, who gave an account of
animal experiments made by him on the effects of
inhaling different kinds of dust.

I have prepared Table I. from the data as to numbers
employed, and deaths in different age periods in different
occupations, as given in the last Decennial Supplement
to the Registrar-General’s Reports, and the Report to
the Home Secretary on the Health of Cornish Miners.

Table I.—Annual Death-rates, England and

	Age 15-20.				Age 20-25.				Age 25-35.				Age 35-45.				Age 45-55.				Age 55-65.			
	di		CO		d5		co		di		co		o		1 .  co		0)		CO		di			
			CD c/>		eg		<x>		•co nJ		d)		co				diseas		d>		co		d>	
	co  'fl		§ O		<x> co 'S	"fl  o	fl cd O		d)  .co  'fl	fl <X»	fl  !		dises	'fl	fl o			fl  dj	§  Q		d>  .co  'fl	"fl  <D	co fl cd o	
	fl fl	*o	Jp	O	br fl fl	3 ’o	<X>  .fl	o	be fl fl	'o  Q	d)  .fl	3 o	be  fl  fl	^A  '5  Q	d>  rfl	7a  o	bo  fl  fl	rs  ‘5  o	.fl	7a  Q	he  fl  fl	.'fl  *3	CP  .fl	Ta  o
			O	H	i-q		o		R1		C				o		Hl		o		.•-1		O	Eh
All occupied males	0'8	0*4	1*0	2'2	2’0	0'5	1*9	4*4	2*8	0*6	2*6	6*0	4*4	0*7	5*1	10*2	63	1*0	10’4	17*7	8*7	1*3	21*0	31*0
Farm labourers...	0'5	0'4	0'8	1'7	1*3	0*6	1*6	3*5	1*5	0*5	2*1	4'1	2*0	0*7	3*3	6'0	3*1	0*9	6*6	io*e	4*4	1*3	13’6	19*3
All coal miners ... Coal miners,Notts	0'7	1'2	1'3	3*2	1*4	1*2	1'9	4*5	1*6	1*2	2'1	4*9	2*4	1*6	3*6	7*6	4*8	2’1	7*8	14*7	12*0	2*8	21’2	36*0
and Derbyshire	0*6	0*9	1'0	2'5	1'3	0*9	1*5	3*8	0*9	0*9	1*5	3’3	2’2	1*0	2'8	6*0	2*8	1*1	7*3	11*2	8*9	2*3	20*0	31*2
Ironstone miners Miners living in	1*0	1*6	0'5	3*1	0'7	0'7	1*6	3*0	1*9	1*5	1*9	5*3	2 4	1*4	2*8	6’6	5*6	1*4	5*2	12*2	8*7	3*0	16*3	28*0
Cornwall 		0*7	0*5	0*5	1'7	2*7	1*7	1*4	5*8	17*3	0*8	2*8	20*9	33*2	0*6	3*2	39*0	32*2	1*3	11*1	44’6	42*6	0’5	27’4	70*5

On glancing at this table it will be seen that among
the miners living in Cornwall (including large numbers
of men who have worked in the Transvaal) there is a
great increase in mortality after the age of 25 or more,
and that this increase is due -to lung disease (mainly
phthisis). The increased death-rate from this cause
dwarfs entirely the death-rate from all other causes put
together. A similar disproportionate increase in mor-
tality from lung disease with increasing age is seen in
various other occupations in which men are exposed to
dangerous dust.

The table also illustrates the w’ell-known fact that
coal mining is at present one of the relatively healthy
occupations, and that, up to the age of about 55, coal
miners, though they are very much exposed to inhala-
tion of dust have an exceptionally low mortality from
lung disease (especially from phthisis), in this respect
resembling the agricultural classes. So striking is the
freedom of coal miners from phthisis that it has even
been supposed that coal dust protects the lungs from
phthisis. As, however, ironstone miners are equally
fi ee from phthisis, there seem to be no real grounds for
this supposition. The truth is that mining itself is a

thoroughly healthy occupation, provided that the excep-
tional dangers which are apt to be associated with it
are avoided.

Harmless and Unhealthy Dusts.

From coal mining experience it is evident that the
breathing of dust in moderate quantity is not necessarily
unhealthy. On the other hand, the mortality statistics
and other evidence in connection with metalliferous
mining show that the breathing of certain kinds of dust
is extremely unhealthy.

Unfortunately, it has not proved possible as yet to
specify exactly, either from physical examination or
chemical analysis, what kinds of dust are harmless, and
what kinds harmful, when breathed. Human experi-
ence enables us to say, however, whether or not certain
varieties of dust are, as a matter of fact, dangerous or
not.

It seems quite clear, in the first place, that fine dust
from uncombined crystalline silica is dangerous. A
typical example is the quartz dust produced in mining
the gold-bearing quartz reefs in the Transvaal. Another
example is the dust from powdered flint, used in the
pottery industry. The dust from granite in Cornish
mines, and in the granite-cutting industries, is another
example. Granite is a mixture of crystalline quartz with
the silicates mica and feldspar; and presumably the ill-
effects are mainly due to the quartz. Other examples
are the dust from ganister, hard sandstone, millstone
grit—all forms of crystalline silica.

On the other hand, there are many forms of inorganic
or organic dust which are known to be practically harm-
less. Instances of these are chalk, clay, various silicates
or aluminates, such as those of Portland cement, and
the dusts from soft limestone, coal, haematite, and other
iron ores. In the case of dust from hard materials other
than crystalline silica, the evidence from human experi-
ence is still somewhat doubtful. It is known, for
instance, that dust produced in the grinding or polish-

Wales, 190C-1-2, per 1,000 Living at each Age.

ing of steel causes phthisis; but whether the danger is
due to the steel dust as well as to that from the grind-
stones or emery is somewhat doubtful. The fact that
phthisis as well as lead poisoning is very prevalent
among file cutters, who are exposed to a mixture of dust
from metallic lead and steel, would seem to indicate that
steel or metallic lead dust is dangerous, since exposure to
dust of lead compounds does not by itself seem to predis-
pose to phthisis. The dust from emery (a form of alumina)
would also be a somewhat doubtful case, but for the
results of experiments on animals. Equally puzzling is the
case of the dust from various hard stones, containing
perhaps 70 to 80 per cent, of silica, partly combined as
silicates, and partly free. Although these stones are
very hard, and contain much uncombined silica, it seems
that little danger may arise from breathing the dust
produced from some of them. In the Cripple Creek gold
mining district, for instance, although the rock is very
hard, and contains over 70 per cent, of silica, and (as I
convinced myself by personal examination) much dust is
produced by rock drills and blasting, I was unable to hear
of cases of miners’ phthisis, though some of those from
whom I made enquiries were familiar with the disease