Williams news., 1921-04-29
Bureau of Mines Conducting Mi- croscopic Investigation at
 Pittsburgh Station.
OLD TESTS ARE UNRELIABLE
Reinhardt Thiessen, Research Chem ist, Says Scientists of the Past Only Had Vague Idea of
 the Composition of Coal.

washington.-Conc of the or
 tgin, 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
 harlt 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 its con-
 stituents, the transformation they have
 undergone, and the conditions they
 now are in.
 The chemist did not have enough
 fundamental knowledge to attack its
 chemistry in the right directions. The fuel engineer, in turn, did not have a broad enough chemical basis for stud tes 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 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 a more exact knowl- edge of the nature of coal in general, as well as to obtain certain fundamen- tai facts, has been conducting at its 61IISDuISn SCdIlOn a microscopic SIuuy of the structure of coal. One of the great hindrances to its 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 1 cd was pursued, bits of coal being ei- ther 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 its 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 pa1eobotanists 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 a mixture of Canada balsam and marine glue. The piece was ground to a safe thickness on lapidary's wheel and was finally ground to trans parent thfnness by hand on a fine hone. Examinations were then made through the microscope at magnificatfons rang Ing up to 2,OOO diameters.
 The bureau says that even with the naked eye a bed of any bituminous coal is readily seen to be banded and 3 chunk of coal is seen to be highly animated and composed of layers greatly in thickness and in color, texture and fracture.
 There are generally recognized and described two kinds of coal with re- 'pect to its texture; compact coal and mineral charcoal or mother-of-coal In he compact coal, in general, two kinds , If bands are recognized, apparently f alternating and in sharp contrast The ! me is of bright jet-black, pitchy ap- f and breaks with a conchoidaI , mooth, shiny fracture. The other is f .rayish black, of dull appearance, a nd breaks irregularly. The former Is n eneraIy called bright coaI' or "glanz n Oal'' and the latter dull coaI'' or f matt coal" The bright coal consists V