May 2, 1913. THE COLLIERY GUARDIAN. 907 before. After the tube had been cleared by repeated explosions the flame went right through as before. The tube was cleaned out before each fresh insertion of dust- It thus appears that when the dust was only put for a distance of 3 ft. along the tube it failed to arrest the explosion because at that distance the gas flame had not attained sufficient violence to stir up the dust, and that it needed to go nearly 4| ft. to obtain sufficient force to raise a dust cloud. This supposition was strengthened by the fact that dust near the closed end always appeared undisturbed. The flue dust appeared to give the same results as stone- dust. Other dusts were tried, and almost all of them succeeded in putting out the flame. Even sand proved successful. When the gas was lit at the open end of the tube so as to produce only a gentle inflammation of the gas without an explosion, this inflammation passed over the dust without being checked, probably because there was not sufficient violence to stir up the dust. Magnesia appeared to be too light, and was puffed away at once. The experiments were discontinued after 66 shots by reason of the repeated shattering of the tube during test shots when no dust was present. FUNDS OF TRADE UNIONS. Part C (Trade Unions) of the reports of the Chief Registrar of Friendly Societies gives particulars of the funds of registered trade unions at the end of 1911. At the close of that year there remained 680 unions on the register, of whom 585 made returns, with a total membership of 2,361,174; of these, 52, with a member- ship of 622,160, are included in the mining and quarrying group. The latter had a total income of £821,025, the average contribution per member being £1 Is. Id., and the average amount of benefit paid 18s. 4d. The averages for all trades were £1 7s. 6d. and 19s. respectively. In the mining and quarrying group the proportion of each £100 of income expended in the four principal classes of benefit was as follows:— Unemployed, travelling and emigration benefit, 8 42 per cent.; dispute benefit, 40’50 per cent.; sick and accident benefit, 12 91 per cent.; funeral benefit, 2’27 per cent. The proportion expended on dispute benefit compares with 16’57 per cent, for all industries. Under the head of management and othei’ expenses, the proportion expended was 13’58 per cent. As regards funds, on December 31, 1911, the mining and quarrying unions were the richest of all the groups considered, possessing £1,855,231 out of a total of £6,326,712, &c., returned ; this total, however, repre- sented a decrease of £3,049 on the year. The funds per member worked out at £2 19s. 8d., as compared with £2 13s. 7d. for all industries, the decrease on the year being 2s. 2d. per member. It is interesting to note that of the total funds held by the mining and quarrying unions at the close of 1911, 50’7 per cent, was in the form of cash in hand and in bank, 43’5 invested in Government and municipal securities; 0’8 per cent, in mortgages, and 4’2 per cent, in land and buildings. It is necessary to observe that the general strike in the spring of 1912 effected a radical change in the financial position of the miners’ unions—an influence COAL SAMPLING AND ANALYSIS.* (Continued from page 855). COAL ANALYSIS AND SIZING. 1—Standardisation of Proximate Analysis of Coal. A.—Preparation of Fine Sample. Reduce the sample which has passed the 5/16 sieve to about one-quarter of its bulk—say, to 1J lb.—and crush the whole of this by any convenient means (but avoid heating the sample by friction) to pass a 60-mesh sieve. If, however, the original coarse sample is obviously wet on the surface, the prescribed quantity of 1 j lb. shall be previously air-dried at about 30 degs. Cent., and the loss of water noted for report. B.—Determination of Hygroscopic Moisture. Weigh out not less than 1 gramme of the prepared sample so as to form a thin layer in a flat dish (or low crucible) of platinum, glass or porcelain, and then dry by heating for one hourf in a steam bath maintained at the boiling point. The containing vessel must previously have been heated and cooled in a desiccator before use, so as to eliminate the absorbed moisture. The dried coal must be cooled in a sulphuric acid desiccator for 10 minutes (and not more than 20 minutes) before weighing. The latter operation must be as expeditious as possible. The loss of weight represents the hygro- scopic moisture. If the drying process is continued too long, the coal may commence to gain weight by oxida- tion. C.—Determination of Ash. Weigh out not less than 1 gramme of the prepared sample into a flat dish, preferably of platinum, and burn off the organic matter, starting slowly M first so as to avoid “ dusting,” and then ignite to constant weight. Great care must be taken to see that no particles of unburnt carbon are enclosed by the grains of ash. Cool for 15 minutes in the desiccator as before and weigh. Weight, less dish, equals ash. D.—Determination of “ Volatile Matter.” In this case not less than 1 gramme of the prepared sample must be weighed into a platinum crucible with a close-fitting lid, both of which have been previously prepared by heating and cooling in the desiccator. Heat this, in a place free from draughts, over a gradually increasing flame of a bunsen burner (or equivalent arrangement) until the sample ceases to give a flame at the lid, and thereafter for one half-minute exactly at a bright red-heat. The upper surface of the lid should burn clear, but the under surface should remain covered with carbon (from decomposed tar). Transfer for cooling to desiccator, taking great care not to displace the lid and admit air. Weigh after 15 minutes, and loss of weight is moisture plus “volatile.’’^ F.—Determination of Fixed Carbon and Sulphur. The former is to be calculated by difference. Sulphur must be determined by the Eschka-Fresenius method, as follows, unless determined from the Mahler- bomb residue:— Weigh out 1 gramme of the fine coal into a platinum dish of 70 to 100 cubic centimetres capacity, add 15 gramme of the magnesia-soda mixture (2 parts light magnesia, plus 1 part anhydrous sodium carbonate intimately mixed), and mix intimately with the coal. Heat very cautiously at first with gradual rise of temperature. After the evolution of gas has ceased, raise the temperature until, after about 15 minutes, the bottom of the dish is at a low red heat. Stir occasionally towards the end when the carbon has disap- peared. Transfer the cooled residue to a beaker and rins^ out the dish into the beaker with 50 cubic centimetres of water and boil, adding about 15 cubic centimetres of strong bromine water, for about five minutes. Filter and treat thf- undissolved residue twice with 30 cubic centimetres (each time) of boiling water, and finally transfer to the filter and wash. To the combined extract (about 200 cubic centimetres in volume) add 15 cubic centimetre of strong hydrochloric acid and boil off the bromine. Have a 10 per cent, solution of barium chloride ready boiling, and add 10 cubic centi- metres of this to the boiling extract, adding it drop by drop at first, with constant stirring. Allow to stand on a hot plate until perfectly clear, then filter off through a “ barium” paper and wash thoroughly with hot water to remove barium chloride. Dry the paper with barium sulphate slowly on the lid of the platinum crucible or otherwise, and burn the paper as usual. Keep at a red heat some time to re-oxidise any barium sulphide, cool in the desiccator and weigh. A blank determination, under similar conditions without the coal, should always be done, and the result representing the sulphate impurities in the materials used deducted. * Extracted from reports issued by the South African Engineering Standards Committee. t The Committee finds that there is no appreciable difference in the drying effect between 90 degs. Cent, and ICO degs. Cent. J “Volatile matter ” is not necessarily entirely of hydro- carbon nature, but may include chemically combined water and “ water gas,” which, of course, is outside the province of this report. Some brief particulars, however, relating to the more important organisations in the coalmining industry are given hereunder:— Funds No. of December 31, members. 1911. £ Yorkshire'Miners 92,900 ... 373 091 Durham Miners 132 014 ... 464 667 Northumberland Miners 39 547 ... 81.887 Nottingham Miners 31,868 ... 207 869 Derbyshire Miners 38 928 ... 345 530 South Wales Miners 116,863 ... 115,890 Lancashire and Cheshire Miners 69,154 ... 70,626 No particulars are given in regard to the Scottish miners’ unions. The late Earl of Crawford and Balcarres left unsettled property of the gross value of .£436,279, of which the net personalty has been sworn at £321,509. Grimsby Coal Exports.—The following is the official return of the exports of coal from Grimsby during the week ended the 24th ult.:—Foreign: To Antwerp, 452 tons; Cronstadt, 2,358; Dieppe, 1,205; Drammen, 1,182; Esbjerg, 1,328; Gothenburg, 2,659; Hamburg, 744; Hargshamn, 1,670; Helsingborg, 1,727; Lemvig, 1,114; Malmo, 1,532; Oxelosund, 1,941; Reykjavik, 1,164; Rotter- dam, 420 ; Solvesborg, 1,285; Trondhjam, 737 ; and Wisby, 1,681; total, 23,205 tons. Coastal—To Gravesend, 475; Lerwick, 700; London, 101; South wold, 60; and Whitstable, 262 ; total, 1,598 tons. For the corresponding week of last year the exports were 13,718 tons foreign, and 794 tons coastal. | As some of the sulphur may be present as sulphur- dioxide in the gasps remaining after a bomb determina- tion, the following procedure is recommended:— After the burning of the coal, the gas during its exit from the bomb is bubbled through a 5 per cent, caustic soda solution contained in an Arnold’s bulb or a cylindrical measuring-glass. This solution is emptied into a beaker and, after removing the capsule containing the ash, the inside of the bomb is carefully washed into the beaker. Next the ash is emptied, and the capsule rinsed, into the beaker. The whole is then boiled with 5 cubic centimetres of saturated bromine water, filtered, and the procedure detailed above in Eschka’s method followed, commencing by addition of hydrochloric acid. By determining separately the sulphur found in the ash, an approximate estimate is made of that present originally as sulphates, the difference between this and the total sulphur representing that present in the form of sulphides or in organic combination. It is recommended that, unless reason is known to the contrary, the amount of sulphur shall be assumed to be equally distributed between the volatile matter and the ash—i.e., half the sulphur is to be subtracted from the volatile and half from the ash, in making up the analysis to 100 per cent.; but the analyst’s report shall in such case say that this has been done. 2.—Standard Treatment as Regards Moisture in Coal. With Special Reference to Calorific Valuation. Should the coal arrive at the laboratory obviously in a wet condition, two methods may be resorted to before the combustion experiment. The first consists in allowing the coal to dry in the atmosphere of the laboratory by spreading it out on a dry non-absorbent surface in a layer abdut I in. thick, and turning it over occasionally until all traces of surface moisture have disappeared. No artificial heating or exposure to the sun is permissible during this operation of air-drying, and as soon as the air-drying is considered to be complete the coal should be ground and bottled as quickly as possible. In reporting, the statement would be made that the “coal air-dried” had been used, and the readings of the wet and dry bulb thermometers may desirably be stated on the report. Since the amount of water which is thus given off depends on the actual amount present in the atmosphere at the time and place of drying, consistent results are to be expected only by completely drying the sample. The second method which may be adopted, unless the sample is too wet, is to crush the sample as above and then determine the percentage amount of moisture by drying a weighed quantity for an hour at the tempera- ture of the boiling point of water, after which the calorific value is determined on the sample thus dried. The crushing must be as expeditious as possible. In such cases the report should state, in addition to the evaporative power of the samples thus dried, the percentage amount of water present in the coal as received, and the temperature at which this determina- tion was made, viz., the boiling point. 3.—Standardisation of Determination of Calorific Value. The “ evaporative power ” of a fuel is defined as the gross amount of heat (lb./lb.) given out as such fuel, when completely burnt in the standard calorimeter under standard methods of working specified. No deductions (other than those involved in the formula) from this gross quantity of heat shall be made for combustion of either the whole, or a part of the nitrogen or sulphur contained in the fuel. When coal is sold on its heating value, this value shall be the “ evaporative power” as defined above, and not the “net calorific value.” The standardisation which the Committee has undertaken refers exclusively to the Berthelot bomb as modified by Mahler and later inventors. No special type of instrument of this class is recom- mended, but the following points must be attended to:— (a) The metal of the water vessel should be capable of a high polish, which must be preserved in use. (b) The water-equivalent must be low—i.e., both vessel and bomb should be made of metal of as low specific heat as possible, and the best results will be obtained from bombs of light weight, so long as they are strong enough. (c) Water Jacket.—The calorimeter shall be surrounded by a water-jacketed annular vessel, containing at least four times as much water as is used in the calorimeter. (d) The insulation of the water vessel of the calorimeter from the outside water jacket should be rendered as perfect as possible by use of non-conducting supports. (e) The temperature of the water in the outer jacket must be adjusted before use until it does not differ by more than 2 degs. Cent, from that in the calorimeter, but by preference it should be slightly warmer than the inner, so as to make the factors in the radiation correction opposite in sign and'thus diminish the correction.