The Barre daily times. (Barre, Vt.) 1897-1959, 1922-08-02
BARRE DUST UNDER
THE MICROSCOPE
Bureau Of Mines Investigator Tells Of
Discoveries Made in Analysis
Of Sugar Tube Tests.

Long awaited results OF the investi
ration made by the e. 8. bureau q
mines in the fall and winter of 1920
81 are now at hand in the form OF 9
report submitted by Sidney Il kat2
and L. j. Trostel to the Journal OF the
American Society Of Heating and Ven.
tilating Engineers. 1t will be recalled
that Mr.. Katz, who is attached to the
research laboratory of the bureau in
Pittsburg spent several weeks in the
Barre district
His investigation supplemented the
statistical and medical inquiries con-
Quoted BY others. Under the caption,
"Dustiness Of the Air in Granite Gut
ting Plants" Mr.. Katz, in collaboration
with Mr.. Trostel, writes inforlningly OF
his observations in the plants OF Bar
clay Bros. well-Wetmore Co.,
Grearson 4 Lane, Harrison Granite Co.
and Jones Bros. Co.
Mr.. Kratz arrives at some rather
positive conclusions and in summariz-
ing the results Of his Investigations
along various lines he invariably adds
that Barre is the granite center of the
world and that what goes for Barre Is
pretty apt to apply wherever granite
is cut.
Barre, w. he says, lis the largest
granite quarrying and cutting center
in America, and is thus a fertile field
for observation Of granite working
trades. Recently statistical and med
zeal study was conducted there for the
purpose of learning methods of pre-
venting disease, to improve upon the
course of treatment, and to determine
the conditions which lead most readily
to the complaint. For this purpose it
was to have Information concerning
the dustiness of the air. Such data are
also of value for comparing dust-re
moving devices and suggesting means
for their improvement.
THE u. s. bureau Of mines, in con-
formation with its policy of improving
health conditions in the mineral indus
try, undertook this investigation. The
results obtained are doubtless typical
Of conditions existing in the entire
granite industry"
Labor in the plants in divided by Mr..
KATE into four classes: Roughers, sur
facers, finishers and muckers or help
ers. He does not consider that sawyers
and polishers are exposed to the dust.
He describes in detail the plants in
which the Investigations were carried
on. He was anxious to study dust con
ditions in a variety of stonesheds and
to that end extended his inquiry
through FIVE plants.
By TIE bureau of mines the sugar
tube method for determining rock dust
in air has been considered standard
method for many years. 1t was used
in the Barre investigation, although
the konimeter and the Hill dust count
er were also utilized and the results
compared.
The sugar tube contains small re-
GERS for holding the screens which sup.
port the sugar. Mr.. Katz says "The
method of dust determination consists
in passing a measured volume Of air, |
by means of a calibrated foot pump
through tube containing graduated |
sugar, which filters and retains the sus-
pended dust. About one cubic foot of |
air per minute is filtered and about |
fifteen cubic feet constitute sample |
The sugar tube and included dust are
then sent to a laboratory. The sugar is
dissolved in water, and strained through |
a fine screen which removes particles
about 20 microns in diameter q micron
equals $4,000 in.).
"A small aliquot part q eli. mm.l is
examined under a microscope at ITO
diameters magnifcation, and the inso-
luble particles of rock dust are usually |
divided and counted into particles |
above and below 10 mierons in diam
eter.
"Roughers were found to breathe /
most dust, 10 ing. per Gu. nm by
weight and number 3.574 particles per
&C. They are followed by finisbers who |
breathe 1891 particles. and then by |
surfacers breathing 1856 particles. Sur
facers working outdoors inhaled slight |
" more dust than indoors, showing |
that the dust removal systems were of |
value
"The most air was breathed by the
roughers when using the small pick OPP |
Grated by an sir-hammer, in fact. this
is responsible for the high
average for roughers. The pick creates
excessive dust, and as the workers
nostrils are usually not more than two
feet from the rock, an exceedingly
dusty air il inspired. Roughers breathe
much less dust when using the old
fashioned hand hammer and chisel"
In suggesting methods for deducing
iustiness. Mr.. Katz says:
"A standard Of mig. Of dust per
u. in. of air has been proposed for the
rold mines of the Rand of South Afri-
"a, as a maximum tolerable limit. AL
Ihough II is possible that the sugar
lube used by the bureau Of mines re-
aims somewhat more dust than the
'uear-tube used in South Africa. never
Iheless. only six samples in los were
,elow the mig. limit; and the general
average OF " mg. for Ave plants indi-
'ates that the existing dust conditions
n granite cutting plants can be i'm
proved
in fact. the manseements have
the dustiness by the appli-
alton Of vacuum systems TO indoor
Iurfacing machines from which dis
hargcd dust accumulates in consider
'ble bulk. and rule Of the Barre
ranch Of the international Granite
'utters' association Of America requires
inishers 20 wet their work for the pur-
lose Of allaying dust; but in few in
tsnces was the practice observed.
1T IA not the object Of this nauer