Show coal structure being StiLla studied died bureau of mines conducting microscopic cro investigation at pittsburgh station OLD 10 TESTS ARE unreliable reinhardt thiessen research chemist says scientists of the fhe past only hild hd a vague idea of the composition of coal wash washington agton conceptions or of the origin composition and general nature of coal held by scientists in the past are so different and contradictory that it Is a difficult matter to determine deter mine the real extent of knowledge available or to rely on the literature says reinhardt thiessen research chemist of the bureau of mines scientists in general had bad only a vague idea of the composition of coal the origin of its constituents the transformation they have undergone awl the conditions they now are in tile 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 tor for studies in combustion distillation cooking C and other processes relating to the use of coal hence the efficient utilization of coal in the industries lias has suffered from the lack of a proper lits 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 knowledge of the nature of coal in general is as well as to obtain certain funda fundament men tal tai facts has been conducting at its pittsburgh station a microscopic study of the structure of coal one ot of the great hindrances to its study from the time of the earliest investigators to tile the present has been the difficulty in preparing thin sections for observation many attempts lid had been made bade to overcome this difficulty and also to devise other means of study for a number of years the method was pursued bits of coal being either totally or partly burned and the ash examined under the microscope later maceri maceration stion was tried with lilt some success but on the whole it tailed failed to r reveal even the true nature of coal diore recently the method was tried of fit softening the coal with mith reagents and then cutting it into thin sections with a cr 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 ts in studa lug rocks and botanists in studying plants was employed A small rectangular piece of the coal to be exall ned was P planed luned and polished on one surface which was then cemented to a glass ilde glide with a mixture of canada bal balsam aam and nd marine glue the piece was ground to a sate safe thickness on a lapi darys wheel and was finally ground to transparent thinness by hand on oil a fine hone E laminations were then made through life microscope at magnifications ranging up to diameters the bureau says that even with the naked linked eye a bed of any amy bituminous coal Is readily seen to be handed bonded and a chunk of coal to Is seen to be highly laminated arid and composed of layers varying greatly in thickness and in color texture and fracture there are generally recognized and two kinds of coal with fill respect to its texture compact coal arid and mineral charcoal or mother ot of coul coal in the compact coal in general two kinds of bunds bands are recognized apparently alternating and in sharp contrast the one Is of a bright jet black pitchy appearance pe arance and breaks with a conc holdal smooth Bino olli shiny fracture the other Is grayish black of a dull appearance and all breaks irregularly the former Is generally called bright coal or alani re coal ai aud and the latter dull coul coal or batt cohao cool TU bright coal of masses greatly varying in in thickness and breadth and entirely surrounded by or Im bedded in the dull coal front from the study at high magnifications it has been definitely shown that the bright coal represents constituents that at one time were pieces ot of wood as of trunks steins brunches branches and roots they are called the dull coal Is extensively laminated sub into thinner sheets of 0 bright cord coal and dull coal these thin sheets of bright coal also consist of definite components and are ins im bedded in a dull granular appearing matter the dull coal may therefore conveniently be divided into two classes the thin black shiny strips and the highly comminuted com material termed in which they are im bedded derived from plants it Is conclusively shown that the ti in strips of bright coal are also derived from woody parts of plants and are but represent thinner and stin smaller aller fragments than the thicker strips there Is no DO real distinction between the larger and ithe lie smaller or thinner constituents there being a complete range in intermediate sizes but the smaller are the more numerous some coals are largely made up of the thinner thra strips the is composed of a number of groups or classes of constituents most of N which aich can be definitely identified find and their origin determined these are the degradation products of cellulose ellul ose the essential constituent of coll cell walls humic matta spore eaines resins remains of cuticles cubicles cuti cles highly carbonized material and some mill eral matter all are readily distinguishable gui gul la in the photomicrography photomicrographs of a number of foals has shown that most of the coal Is derived from the parts of plants I 1 such as trunks stems branches and roots In including chilling nil all the tissues tissue sr that make up such parts some of wood Is represented by the larger thra some by the smaller an thra and some by the tile proportion represented in each of 0 these varies in different coals and even at different levels in the same coal bed there Is evidence that borne some ot of the cellulose matter Is derived from the wore more delicate tissues such euch as herbaceous plants young or growing parts of plants leaf tissues etc the humli or decayed vegetable matter forms it considerable proportion of tile the of all coals coal sIt it from the parts ot of plants but includes besides ma seraf de bayed wood some macerated ma gm bark pith cortex and other more delicate parts there Is no sharp dividing line between the an and the humic constituents resins are found in all coals but bui in greatly varying proportions both in the and the att Fitus when found in the the resin la 19 found in those tissues where it would bo be expected it if the constituent were still a sound piece of wood in tile the the resins are easily distinguished from the other constituents comparing different coals the eidnes or outer walls of spores fire are present in the only and form an important part of all coals but in greatly varying proportions the spore espnes are the most readily discernible c nible constituents in all coals and have definite characteristics different genera a and ad perhaps different species of eaines differ in sculpturing size form and thickness of wall nall and by met means as of these characters can readily be distinguished from one another the spore characters have been so we well 11 preserved in almost all coals that the spores of one kind of plants can be clearly distinguished from those of another kind la some coal seams scams the larger bulk of the spore exibee are of the same und in other seams two or three kinds may form the main bulk in comparing coals front from different beds predominating the eaines of one seam are easily seen to be different in some u fly ay from those ot of any other bed thug the coals of different beds containing different spores may readily be dis dib front from one another occasionally in a given coul corn seam scam a spore exine is found that differs from those of any other seam but does not predominate this spore exine may be a distinguishing characteristic of th coal seam in question although not the predominate one this fact promises to be beof of value in the correlation of coal seams the pittsburgh seam for example contains a small spore exine that Is both predominant and characteristic and may thus be easily distinguished from any other all ordinary bituminous coals contain certain constituents that are more lilg highly gaily curb carbonized than the rest of the coal and stand out in sharp contrast to it on account of their opaqueness in general there are two types of carbonaceous bonace bounce ous matter one type shows 1 definite I ef plant structure and consists of the more highly carbonized parts ot of fill plant a nt cells or bits of woody tissues or other plant tissues the other shown show no plant structure and Is of indefinite Inde unite origin other constituents that are invariably present lu in all coals are the so called rodl etil or needles many are scattered helter through the Sollie sometimes times they are present in such large numbers that they forni form a considerable part of certain thin many of the anthrax Ion compo aerts and conspicuously many of the mineral charcoal constituents a smaller or larger number of that are evidently part of their structure most lost of the tissues remaining la in the coul coal with 4 are associated are recognized recognize d to be those of plants related toa the well known plants allied to the cycads from this it appears that some home ot of the rod lets if not fill all are tho the send petrified contents of tile hie mucilage canals of illie plants in tile original plants these canals were elongated intercellular spaces Nu summing cumming substances |