464 THE COLLIERY GUARDIAN August 28, 1914. much greater in those samples taken within 10 ft. of the outcrop than it is in the normal unaltered coal. In other words, the moisture in the weathered coal appears to be more largely in a combined form, and to have thus a lower vapour tension at the temperature of air drying. This is a property shown also by lignites and sub- bituminous coals. A further point of similarity is that the weathered coal, like the lignitic types, forms a deep- coloured, possibly colloidal, solution when treated with hot dilute sodium carbonate solution. In these respects, as well as in ultimate chemical composition, the weathered coal bears marked resemblance to the lignites. The resemblance in composition may be seen from the following table of comparative analytical results :— Ultimate Composition of Various Coal. . Constituents computed to ash . and i moisture *. •S a free basis. Tie k fl ce 5u CO Source of coal. o' O r fi o rQ 6 . fl CD be o efl Jo 2 2 x 75 rfl >» Ct rfl ce O O O Per Per Per Per Calo- Per cent. cent. cent. cent. ries. cent. Texas lignite 10'7 ... 72'09 .. . 5'14 ... 20'54 .. . 6,921 . .. 2'57 Montana ’ignite ... 8T ... 67'50 . 4'70 ... 25'96 .. . 6,219 . .. 1'45 Wyoming sub-bitu- minous coal ... 19*9 ... 74'40 .. .4'94 ... 18'02 .. . 6,9h3 2'69 Experimental mine, weathered coal ... 12'4 ... 75'81 .. . 3'89 ...18'10.. . 6,946 1'63 Experimental mine, unweathered coal 2'1 ... 84'43.. . 5'56 ... 6’74.. . 8,408 . .. 4'72 * H - — 11 8 Fig. 5—Curves showing Variation in Volatile- matter Content and in Calorific Value of the Samples on Moisture and Ash-free Basis. o o 13000 14500- ■ 12000- 15000 14000 13500- 12500- 35 100 600 700 K Pgg40. 200 300 400 500 DISTANCE FROM OUTCROP, FEET samples. The outcrop coal is considerably lower in hydrogen than the lignites, and, furthermore, as is shown later, the weathered Pittsburg coal differs from the lignitic coals in having much less power of absorbing oxygen.* These facts suggest the probability that the Pittsburg coal, through its reaction with and assimila- tion of oxygen in weathering, has not formed the same type of substance—the chemically unsaturated substance —that is present in the lignites. The lignites, as com- pared to the weathered coal, are the product of changes 3 1800 2100 2700 2400 900 600 300 50 100 200 250 300 150 TIME, DAYS W e o 0 1500 « 1200 n Fig. 6.—Rate of Absorption of Oxygen by Three Samples of Coal from Experimental Mine. that have taken place out of contact with the air, and contain substances richer in hydrogen and probably of a different chemical structure as regards oxygen and hydrogen linking. * The rate of absorption of oxygen by sub-bituminous Wyoming coal is shown by experiments reported in Technical Paper 2, Bureau of Mines (p. 10), to be three or four times the rate found in the present study for the outcrop Pittsburg coal under similar experimental conditions. An outline of the method used in examining the coal samples in respect to their oxygen-consuming and gas- liberating properties has already been given. The results are shown in figs. 6 and 7. It is to be noted that the outcrop coal 5 ft. in, although still retaining some oxygen-consuming power, is much less active in this respect than the fresh coal. The coal 50 ft. in shows also less activity towards oxygen than the fresh coal, although during the first few weeks of the test the difference was slight. The oxygen-consuming test thus appears to be more delicate than the chemical analysis, because the latter indicated practically no deterioration in the 50 ft. coal. Furthermore, a slight but unquestionable production of inflammable gas occurs in the case of the fresh coal, whereas none could be detected with the 50 ft. sample, and only a slight amount, almost within the error of the analytical method, in the case of the outcrop sample. It is evident that the Pittsburg bed of coal, as situated in this mine, has suffered alteration by weathering up to a distance of about 50 ft. from the outcrop so as to cause a marked reduction in its power to consume the oxygen of the air and to liberate inflammable gas. The calorific value and carbon and oxygen content of outcrop coal of the Pittsburg bed are nearly the same as those of Texas lignite and Wyoming sub-bituminous 250 125 150 TIME. DAYS O 6 150 J o i K 50 o Q Z. 6 I ’00 » 75 Fig. 7.—Rate of Liberation of C02 and CH4 by Three Samples of Coal from Experimental Mine. The liberation of CO2 by the coal appears to be, in some measure at least, a result of the absorption of oxygen, although it does not appear simultaneously with the absorption, but subsequent to it. The amount of CO2 produced is less than the molecular equivalent of the oxygen consumed. The outcrop coal and the 50 ft. sample produce CO2 in greater quantities than the fresh coal, probably on account of the greater proportion of oxygen they have assimilated. It is to be noted further that the Pittsburg coal in this mine, even in fresh condition, is less gaseous and less active in consuming oxygen than the majority of coals from other regions.* The samples compared for inflammability were pre- pared by air drying the coal at 30 degs. to 35 degs. Cent., and then pulverising it to 200 mesh. Comparisons of inflammability were made with these samples in the air dry condition by the laboratory method by Frazer. A given weight of dust was puffed with air over a heated platinum coil, and the pressure developed on ignition was measured. The results are shown in fig. 8 for the three samples from the experi- mental mine. Sample 12282 (622 ft. in), and sample 12492 (50 ft. in) show practically no difference in inflammability. The outcrop coal (sample 12250). how- ever, shows a very much lower degree of inflammability, 240 M 40 80 « 120 § 200 o g 160 5 5.5 6 6.5 7 CURRENT IN IGNITION COIL, AMPERES Fig. 8.—Comparative Inflammability of Pre- pared Dust of Three Samples of Coal from Experimental Mine. due in part to its higher content of moisture and ash, and in part also to its weathered condition. Although the outcrop sample contains about 16 per cent, less of combustible material (ash and moisture free) than the other two samples, its inflammability at the highest temperature of the ignition coil is at least 80 per cent, lower, indicating the large influence of alteration in composition of the coal substance. This effect of weathering on inflammability, which is so evident in the outcrop coal, does not appear to have extended 50 ft. into the coal bed. It is of interest to note that although the outcrop sample contains a much larger percentage of oxygen than the other two samples, this fact alone is not sufficient explanation of its low degree of inflammability, because samples of Illinois coal and Wyoming coal, notwithstanding their high percentages of oxygen, show comparatively high degrees of inflammability. Because of the prevailing prejudice against coal having a rusty appearance, and the popular belief that its evaporative power is less than that of fresh-looking coal from the same mine, a series of evaporative tests was made by the steam engineering section of the * Porter, H. C., and Ovitz, F. K., “ The Escape of Gas from Coal ” : Technical Paper 2, Bureau of Mines, 1911. Bureau with two samples, No. 180 taken at the face, 622 ft. inbye the outcrop in the main entry, and No. 179, rusty coal taken in the “ gallery ” entry (fig. 1), 70 ft. from the outcrop. The tabulated figures show no decided difference in the evaporative power of the two samples. The differ- ence between the average over-all efficiency of the tests run with the “ rusty ” coal, and that of the tests run with the fresh coal is so small that it cannot be con- sidered indicative of any actual difference in the quality of the two samples. The tests failed similarly to show that the “ rusty ” coal is inferior to the fresh coal in any other respect. Some observations of the weathering of coal in the Green River Basin (near Rock Springs), Wyo., by Schultz* lead him to the conclusion that although ground water infiltration may affect in some degree the weathering of coal in the seam, the weathering has not, in the locality observed, penetrated to the ground water level. “ If the coal is not open or exposed to the air the weathered zone does not as a rule extend more than 50ft. below the surface.” The opinion is expressed also that coals of lower grade are more easily affected by oxidation than those of higher grade. The ground water level at the experimental mine seems to vary greatly with change of season, and cannot at any time be referred to any particular plane • within the zone of variation. The rusty appearance in the coal, at a few points beyond 100 ft. from the outcrop, indicates that beyond that point there has been infiltration of iron- bearing waters through the coal bed from fractures or joints in the roof, although the chemical composition of the coal seemingly has not been altered. It is likely that the moist condition of the ground through the greater part of the year, or, in other words, the proxi- mity of the ground water level to the surface at most seasons, has retarded the weathering effect upon the coal bed at this locality. It also seems probable that the nature of the roof makes a difference in the extent of the weathering to which the coal bed is subjected; that is, whether the roof is porous or fractured, per- mitting penetration of water, or contains relatively impervious strata, such as the shale in the roof over the Pittsburg bed at the experimental mine. Weathering has affected the Pittsburg bed of coal at the experimental mine near Bruceton, Pa., for a dis- tance not greater than 50 ft. from the outcrop, the amount of cover at this distance being less than 25 ft. This conclusion applies only to the particular mine investigated. Conclusions of general application must necessarily be based on a large number of similar investi- gations of other mines where conditions vary in respect to the amount and the nature of the roof overlying the coal. The weathering effects are manifested in a lower con- tent of carbon and hydrogen and higher content of oxygen in the coal substance, a correspondingly lower calorific value of the coal, the presence of a larger pro- portion of combined water in the coal substance, and a much diminished power of consuming oxygen from the air and of liberating methane. A rusty appearance on the surfaces of lumps is not necessarilv an indication of any depreciation in the fuel value of the coal. GERMAN PATENTS AND TRADE MARKS. Issue of Rules. Rules have now been made by the Board of Trade by virtue of the provisions of the Patents, Designs, and Trade Marks (Temporary Rules) Act, 1914. They provide that :— The Board of Trade may, on the application of any person, and subject to such terms and conditions, if any, as they may think fit, order the avoidance or sus- pension, in whole or in part, of any patent or licence granted to a subject of any State at war with his Majesty, and the Board, before granting any such appli- cation, may require to be satisfied on the following heads :— (a) That the patentee or licensee is the subject of a State at war with his Majesty; (b) That the person applying intends to manufacture, or cause to be manufactured, the patented article, or to carry on, or cause to be carried on, the patented process; (c) That it is in the general interests of the country or of a section of the community, or of a trade, that such article should be manufactured or such process carried on as aforesaid. The Board of Trade may, at any time, in their abso- lute discretion, revoke any avoidance or suspension of any patent or licence ordered by them; and for the pur- pose of exercising in any case the powers of avoiding or suspending a patent or licence, the Board of Trade may appoint such person or persons as they shall think fit to hold an enquiry. The Board of Trade may at any time, if in their absolute discretion they deem it expedient in the public interest, order the avoidance or suspension in whole or in part of any such patent or licence upon such terms and conditions, if any, as they mav think fit. The Comptroller may, at any time during the con- tinuance of these Rules, avoid or suspend any proceed- ings on any application made under the Patents and Designs Act, 1907, and the Trade Marks Act, 1905, by a subject of any State at war with his Majesty. The Comptroller may also at any time during the continuance of these Rules extend the time prescribed by the Patents and Designs Act, 1907, or the Trade Marks Act, 1905, or any Rules made thereunder, for doing any act or filing any document, upon such terms terms and subject to such conditions as he may think fit in the following cases, namely :— * Schultz, A. R., ” Weathering of Coal in the Arid Region of the Green River Basin, Sweetwater County, Wyo,” : U.S. Geol. Survey Bull. 381, 1910.