March 14, 1913. THE COLLIERY GUARDIAN. 557 THE DETERMINATION OF WATER IN COAL. (Continued from page 490.) Conclusions and Recommendations. The work of the sub-committee may be summarised in the following conclusions and recommendations:— 1. It does not appear that at present any means exists for distinguishing by analysis between added water “moisture” (which term we take to signify water of adsorption, i.e., that due to a concentration of water on the surface of the particles) and water of crystallisation or of combination, whatever the latter somewhat indefinite term may be supposed to mean. 2. It is probable that the distinction between moisture and water of combination is of little moment in the case of coal, since the losses of water (a) at ordinary tempera- ture under greatly reduced pressure, and in the presence of suitable means for reducing the tension of aqueous vapour to an inappreciable quantity (desiccants), and (5) at temperatures a few degrees above the boiling point of water, do not differ seriously. 2 3. Coal is a substance which very readily undergoes | oxidation, and the best results in the determination of 5 water are only to be obtained when the coal is treated in an atmosphere containing no oxygen. 4. Coal is a very hygroscopic substance, and before being dried must be properly protected in the laboratory from the effects of changes of temperature or of atmospheric conditions. When dry, it must be protected from any contact with moist air or with moisture in any form until the determination is finished. 5. Unless the initial rate of drying is known to be very rapid, the drying should be divided into two periods, of which the latter is much longer than the former. Unless this is done, it is probable that an almost constant small loss, continued over a very long period, may be mistaken for an inappreciable loss. A consideration of the curve on page 490 (Colliery Guardian March 7) will illustrate this point, which obviously applies with very great force to the “ vacuum method.” 6. When the initial rate of drying is very rapid, e.g.^ at 105 degs. or thereabouts, the gain of weight by oxidation may very soon become greater than any loss due to a very slow rate of drying over a long period. 7. There is no advantage to be obtained by drying coal at temperatures above that of the atmosphere but below, say, 105 degs. Cent. Those who have read the body of the report, or who have even carefully read the above conclusions, will not need to be informed that the accurate determination of water in a small sample of coal is a matter of difficulty, and requires grave consideration. In the case of large samples of relatively coarse coal, the matter is of even greater difficulty. We put forward the following recommendations, believing them to be sound, and having due regard to the require, ments of both the industrial and the research chemist; but we do not suggest that they are final. We do, however, ask that workers shall give them serious consideration with a view to their adoption. We recommend that:— 1. Whenever possible, especially in the case of very moist coals, the water in the original sample should be determined after it has been subjected to a minimum amount of preliminary mechanical treatment (e.g., thorough mixing with rapid crushing of lumps), by either of the following methods : (a) A carefully weighed portion of from 100 to 500 grammes of coal is spread out in a metal tray and exposed for at least 24 hours to the-atmosphere of the sampling room. The tray containing the coal is then reweighed and the percentage change of weight is calculated. The coal is then coarsely ground in a mill (a ball grinder is best), and the water determined in the ground portion by one of the methods given in recom- mendations 2, 3 or 4. The water on the original sample can then be calculated; or (b) The xylene method used by Dr. Constam, and given in recommendation 5, all results to be calculated back to the original coal. 2. For ordinary technical work, coal should be dried in an oven with a good air circulation for a period not exceeding 1 hour at a temperature not below 104 degs. nor above 111 degs. Cent. It is advised that two portions of 1 gramme should be weighed between pairs of accurately fitting watch-glasses, or in a shallow weighing bottle, which have been heated to the tempera- ture of drying and cooled in a good desiccator, and be dried for periods of | hour and 1 hour respectively the upper glass or lid of the bottle being removed during the period of drying, at the end of which it should be replaced loosely and the covered vessels placed in the desiccator to cool. At the end of the period of cooling, which should be equal to that allowed for the heated empty glasses or bottles, they should be reweighed and samples of coal sent me, some time back, to examination engines, two coke cars with inclined gantry, and coke the percentage loss calculated. The higher result shall be considered as the percentage of water in the coal. The required temperature can be obtained by the vapour of boiling toluene (111 degs. Cent, at 760 mm.), by steam, at a pressure of 906-1,100 mm., or by an electrically heated thermostatic arrangement. We advise that a long oven, with a door in the small end, should be used. A toluene oven, with a preheating arrangement for the air-current, as described by Siau (Jour. Soc. Chem. Ind., 1911, 61), or other similar device is, in our opinion, Determination of the Moisture Content in Six Samples of Coal (sent by Mr. George T. Holloway, London) OD 02 Loss of weight In a current of coal gas at 100° C. In water oven at 100° C. In air bath at 105° C. After 1 hr. After 2hrs. 1-41 2’81 309 306 7’59 9’63 9’80 9’82 5-42 7’21 7’35 7’19 4*66 5’34 5’62 5’97 4’40 6’85 7’10 7’06 5’32 7’04 7’38 7’22 a practical arrangement. We strongly condemn air ovens and all devices in which the temperature of the walls of the drying chamber is variable. We believe that a fairly uniform temperature in the whole of the interior of ah oven is only to be obtained when the heated walls have an area very large relative to the cubical contents of the interior, and are themselves at a uniform temperature. A preheated supply of air is to be desired. Mere heating without a proper air-current is unreliable. 3. Whenever it is suspected that a coal is specially liable to oxidation or the J hour and 1 hour results differ materially, drying at 104-111 degs. in a current of nitrogen or carbon dioxide is to be preferred to drying in an oven through which a current of air is passing. Either the direct or indirect method of estimating water may be used. If the former is chosen, care must be taken to prove the dryness of the stream of gas which is passed over the coal. The percentage of free oxygen in this gas must, be inappreciable. This method of drying in a current of inert gas is to be preferred for all very exact work. 4. Drying to constant or minimum weight in a vacuum in the presence of sulphuric acid (or other desiccant) possesses no advantage over the last-mentioned method. It is very much slower, and, unless the vacuum is very high, it is better to fill the desiccator with carbon dioxide (or other inert gas) before exhausting. If this method is preferred, a Hempel desiccator, or any other form in which a large surface of sulphuric acid is exposed both above and below the coal, should be used; the coal should be weighed in watch-glasses or shallow weighing bottles and the loss after, say, 24 hours, 72 hours and 144 hours should be taken. With such prolonged periods of drying, the results obtained by this method are practically identical with those obtained by method 3. The air admitted into the vacuous space should always be dried by passing slowly through or over sulphuric acid. 5. The method of driving off water from coal by heating in boiling xylene, and measuring the water which distils over with the hydrocarbon, is a variant of ■ the present time negotiations are in progress with several the method of drying in an inert atmosphere at an prospective purchasers for the sale of some of the land, elevated temperature. It is worthy of serious considera-! The syndicate will control the lines* along which the tion, and although we cannot, in view of the limited ’ development goes, and there will be room for a large information at our disposal, recommend it uncondi-' amount of housebuilding. The scheme is one which will tionally, we consider that it is most promising, and completely transform the Wheatley end of Doncaster. The estate on the Thorne-road side will be utilised for dwellings, while the lower portion behind Wheatley Hall will become the site for factories, works and mills. In time, with the opening out of Barnby Dun, and when the contemplated pit is sunk, there may be a new road built from Doncaster to Sandall and Barnby Dun. The sale, which is sa’d to be one of the biggest deals the property market has witnessed for some time, includes Wheatley Hall, a fine mansion built by Sir Henry Cooke and dating from 1680. It is suggested the Corporation of Doncaster should acquire this as a municipal museum and the park of 103 acres as a public pleasure ground—a thing all Doncaster is at present without. At the Shotton Colliery, Castle Eden, co. Durham, of the Horden Collieries Limited, of Darlington, an extensive installation of new coke manufacturing plant is now in course of completion. This plant will consist of 60 Koppers patent regenerator coke ovens, complete with by-product plant for extracting tar and for producing sulphate of appears to be particularly suitable for industrial purposes. 6. Coal should always be weighed in closed vessels with well-fitting lids or stoppers. Deep vessels such as crucibles are unsuitable for water determinations. Porcelain or metal boats which can be weighed in stoppered or well-fitted sliding tubes may be used. 7. Desiccators with the strongest sulphuric acid, which is frequently renewed, are recommended. If calcium chloride is used it must be ignited before it is put in the desiccator. If phosphoric anhydride is used, it must frequently be stirred. These substances are not nearly as convenient or reliable as sulphuric acid. George T. Holloway, President. J. H. Coste, Vice-President. Appendix. Letter received by Mr. Holloway after the report i ‘ x, J J r | ammonia and crude benzo], together with the requisite had been drawn up : subsidiary plant comprising coal elevating and conveying To Mr. George T. Holloway. machinery, a service coal storage bunker of 1,000 tons In accordance with your request, I have subjected the capacity, an electrical coal charger, two coke pushing for their moisture content, by the following methods.— 1. Heating in a current of coal gas in the water oven at 100 degs; 2. Heating in air in the water oven at 100 degs.; 3. Drying (in air) in the air bath at 105 degs. Cent. (a) for one hour; (b) for two hours ; 4. Storage in a vacuum desiccator over sulphuric acid until of constant weight. The results are set. forth in the accompanying table. In vacuo, over sulphuric acid, at room temperature. After 24 hours. After 48 hours. After 72 hours. After 96 hours. After | 120 hours. After 164 hours. After 168 hours. After 192 houss. After 240 hours. After 264 hours. After 288 hours. After 312 hours. After 336 hours. 2’15 2’33 2’45 2’54 2’54 — — — — — — 3’28 6’27 7’46 8’11 8’44 8’71 8’91 9’08 9’08 — — — 3’70 — 5’28 5’80 6’03 6’13 6’29 6’49 6’61 6’56 6’56 — 1’56 2’35 2’93 3’19 3’39 3’63 3’83 4’04 4’09 4’16 4’28 4’29 3’20 — 4’78 5’41 5’71 5’85 6’12 6’26 6’44 6’43 — — — 4’25 — 5’62 6’10 6’23 6’33 6’50 6’63 6'73 6’66 6’69 6’80 6’08 The values given in the first four vertical columns are the mean of two to three determinations in each case. From the data in the table, it follows that:— (a.) The results obtained at 100 degs. in a current of coal gas were lower throughout than in all the other experiments. In my opinion the method gives incorrect values, which are below the truth. (b.) At room temperature, in vacuo over sulphuric acid, the time required to obtain constancy of weight is so long as to render the method unsuitable for practical application. (c.) The other three series of experiments gave fairly concordant values, those obtained in air in the water over being all slightly lower than those at 105 degs. Cent. (d.) There is no appreciable difference between the two sets of experiments at 105 degs. (In the case of No. 4 test, there is a slight deviation in one of the three individual values after two hours). There is consequently no object in drying for longer than one hour at 105 degs. In my opinion, this method is the most to be preferred. (Sig.) Dr. Th.-Wilh. Fresenius. HIRING AND OTHER NOTES. The sale, by Sir William Cooke, Bart., of the whole of his Wheatley estate at Doncaster marks another step in the development of that town from an industrial and colliery point of view. Sir William has concluded an outright sale of all his land in Wheatley, Bentley, and the neighbour- hood, and his connection with the Doncaster district as a landowner has come to an end. The estate has been pur- chased by an influential syndicate, who propose to lay it out for building purposes, partly as manufactory sites and partly for housing. The land included in the purchase amounts to between 2,000 and 3,000 acres—considerably more than the area of the borough of Doncaster. A great deal of it lies outside the limits of the proposed borough extension scheme, but comes within the town planning area. There have been enquiries from numerous firms for sites in the Wheatley corner of greater Doncaster, and at