The Appeal. [volume] (Saint Paul, Minn. ;) 1889-19??, 1921-04-23
COAL STRUCTURE
BEING STUDIED.
Bureau of Mines Conducting Mi
croscopic Investigation at
Pittsburgh Station.
OLD TESTS ARE UNRELIABLE.
Reinhardt Thiessen, Research Chem
list, Says Scientists Of the Past
Only Had a Vague Idea of
the Composition Of Coal.

the Composition OF Coal.
Observation-Disclosures Of the or
igin, composition and general nature
of coal held by scientists in the past
are SO different and contradictory that
it is difficult matter to determine the
real extent of knowledge available or
to rely on the literature, says Rein
hardt Thiessen, research chemist of
the bureau Of mines. Scientists in gen.
eral had only a vague idea of the, COM
position of coal, the origin of it's con-
stituents, the transformation they have
undergone, and the conditions they
now are in. .-5-
The chemist did not have enough
fundamental knowledge to attack it's
chemistry in the right directions. The
fuel engineer, in turn, did not have
broad enough chemical basis for stud.
les in combustion, distillation, cooking
and other processes relating to the use
of coal, hence the efficient utilization
of coal in the industries has suffered
from the lack of a proper knowledge
of the nature of coal itself.
The bureau Of mines, in order to
clear up some of the confusion that
exists and to get more exact knowl-
edge of the nature of coal in general,
as well as to obtain certain fundamen-
tai facts, has been conducting at it's
Pittsburgh station microscopic study
of the structure of coal. One Of the
great hindrances to it's study, from the
time Of the earliest investigators to
the present, has been the difficulty in
preparing thin sections for microscopic
observation. Many attempts had been
made to overcome this difficulty, and
also to devise other means of study.
For a number Of years the ash meth
cd was pursued, bits Of coal being Ell
Their totally or partly burned and the
ash examined under the microscope.
Later, maceration was tried with some
success, but on the whole it failed to
reveal the true nature of coal. More
recently the method was tried Of sof-
tening the coal with reagents and then
cutting it into thin sections with a mi
crotome. But this changes the coal
too much to show it's true appearance,
besides the method is inexpedient.
Used Rock Method Study.
For the bureaus work an adaptation
of the method used successfully for
years by petrologists in studying rocks
and paleobotanists in studying plants
was employed. A small rectangular
piece Of the coal to be examined was
planed and polished ON one surface,
which was then cemented to a glass
Slide with mixture of Canada balsam
and marine glue. The piece was ground
to safe thickness ON .apidary's
wheel and was finally ground to trans
parent thinness by hand on fine hone.
Examinations were then made through
the microscope at magnifcations rang
ing up to 1000 diameters. II
The bureau says that even with the
naked eye a bed of any bituminous
coal is readily seen to be banded, and
chunk of coal is seen to be highly
Illuminated and composed of layers
varying greatly in thickness and in
color, texture and fracture. '--..- 49,.
There are generally recognized and
described two kinds of coal with re-
spect to it's texture; compact coal and
mineral charcoal or motherzof- coal. In
the compact coal, in general, two kinds
of bands are recognized, apparently
alternating and in sharp contrast. The
one is of bright jet-black, pitchy ap-
pearance and breaks with a conchoidal
smooth, shiny fracture. The other is
grayish black, of a dull appearance,
and breaks irregularly. The former is
generally called bright coal' or 'tglanz
coap and the latter dull coal" or
matt COAL" The bright coal consists
of lenticular masses greatly varying in
thickness and breadth and entirely sur
rounded by or imbedded in the dull
COAL s.., 80 4. )
From the study at high magnifica-
tons it has been definitely shown that
the bright coar represents constitu-
ents that at one time were pieces of
WOOD, as of trunks, stems, branches
and roots. They are called anthrax
ylon." The dull coal' is extensively
sublaminated into thinner sheets of
bright coal" and dull coal" These
thin sheets Of "bright coal" also con.
sist of definite components and are i'm.
bedded in dull granular appearing
J, matter. The dull coal' may therefore
conveniently be divided into two
fclasses-the thin black shiny strips
and the highly comminuted material,
! termed attritus, in which they are i'm.
bedded.
Derived From Plants.
1t is concluslvely shown that the
thin strips of bright coal are also de.
rived from woody parts of plants, and
are anthraxylon. but represent thin
ner aud smaller fragments than the
i thicker strips. There is no real dis.
tinction between the larger and the
]. smaller or thinner anthraxylon constit.
uents, there being complete range in
intermediate sizes, but the smaller are
the more numerous. Some Goals are
largely made up of the thinner an:
] thraxylon strips.
The attritus is composed Of mum.
Der of groups or classes Of constitu.
ents, most of which can be definitely