854 THE COLLIERY GUARDIAN. April 25, 1913. to pass a screen of J in. linear aperture. This is again coned and quartered twice, leaving a reduced sample of about 125 lb. This sample is crushed to pass a screen of f in. linear aperture, being afterwards coned and quartered twice, leaving a final sample of about 30 lb., which is sealed up in a suitable airtight receptacle and sent to the laboratory. Gradually-increasing care is needed in the above operations as the size of the coal is reduced. The labour of the mixing and the coning of the smaller samples is much simplified by pouring them through a funnel, held vertically, having a cylindrical (not conical) spout 2| in. in diameter. If unloading is performed by means of a grab bucket, a large shovelful is taken from each bucket as it comes from the hold, and transferred to the sampling floor. The operations of coning and quartering are then carried out as above. 3.—Bunker Sampling. From Boiler Side of Bunker. Take a square-mouthed flat shovel (size No. 4) and take one shovel quite full at every 5 ft. along the bunker and at the same distance above the floor line, say 2 ft., and put this into a clean sack. The shovel should be pushed into the coal up to where the handle joins the blade, the handle being forced downwards until the shovel is free, and then the whole lifted upwards, keeping the shovel level until the coal is put into the sack. If the bunker side next to the boiler is only provided with small openings opposite each boiler, then it will be necessary to pull out a heap at each place, say about a ton, and sample each heap at three equally distant places, keeping the same distance above the floor line. Generally speaking, the same method is adopted at each heap. In each case it is advisable to take a sample not less than 200 lb. in weight Sampling about 2 ft. above the floor line is recom- mended, in order to avoid coal that has been in the bunker for a long time, or an excess of “ fines ” due to filtration through the coal as it moves, and also to prevent dust and ashes being included in the sample. Reduction and Quartering of Sample. The sample should be placed on a clean, solid floor, that will not break up or mix with the coal, and solid enough to prevent the coal being scattered during breaking, preferably of cement, or better, steel plate f in. thick. A wooden floor should not be used. The whole of the coal should be turned out on the floor, broken down until no pieces larger than 2 in. diameter are left, and thoroughly mixed. It is then spread out in a layer about 2 in. to 3 in. thick, great care being taken that all the sizes are equally distributed throughout the mass. The layer is then divided into four approximately equal parts by drawing the shovel across it twice, and two from diagonally-opposite corners are rejected without interfering with the other two, care being taken to remove all the “ fines,” preferably with a broom. The remaining coal is recrushed and again thoroughly mixed and quartered as above, the same care being exercised. This procedure is continued until coal not larger than T5g in. remains. The quartering is continued until the sample is about 6 lb. in weight, and if more than one sample is required, each sample should weigh not less than 6 lb. When filling the bag with the sample thus obtained, care should be taken that the whole of the sample, including the “ fines,” is placed in the bag, otherwise the sample is unreliable. A east iron street rammer of about 20 to 30 pounds weight with a long handle, is suitable for breaking the coal in the above operation, since the coal does not scatter as much as when broken with a hammer, and since a rammer is far more efficient in the hands of a native for this purpose. In addition to this it will be found advisable to provide a box 2 ft. square and from 6 in. to 8 in. high, open at the top, the bottom consisting of a sieve of T5g in. mesh. The coal is placed in this box and crushed with a rammer through the sieve, the box being lifted from time to time to allow the fine coal to pass through. Crushing to this size, thorough mixing, and careful quartering reduce the sampling error to a negligible quantity. If triplicate samples are required, the two final quarters obtained should be about 20 lb. weight. This should be arranged in a line of about 3 ft. long by 9 in. wide by means of the shovel, care being taken that a proper distribution is made. It is then divided into three portions, and each portion placed in a separate bag, care being taken that the dust belonging to these portions is included. In each bag should be placed a ticket bearing the date of sampling, coal sampled (colliery), size of coal (nuts or rounds, &c.), and name of sampler. The bags are again labelled on the outside with the address, except the check sealed sample, which is labelled on the outside with the same particulars as COAL SAMPLING AND ANALYSIS. Two valuable reports have been issued by the South African Engineering Standards Committee on coal sampling and coal analysis respectively. The reports are presented by the Chemical Sub-committee formed in 1911 with the object of standardising the methods of analysis, &c., of the chemical materials used in industry and commerce in South Africa. It was decided that the subject of coal should first be undertaken with reference to the following:—(a) Standard methods of sampling; (6) standard methods of analysis, including proximate analysis and determination of calorific value; and (c) standardisation of the various sizes of coal for com- mercial use. The results of (a) are embodied in pamphlet No. 1, and those of (b) and (c) in pamphlet No. 2. The following is extracted from the report:— SAMPLING. 1.—Colliery Sampling The sampler should have a thorough knowledge of the colliery, or be accompanied by some person possessing the requisite knowledge. His equipment should consist of a canvas sheet about 10 ft. square to catch all the coal picked down, two sharp single-ended picks of 3 and 5 pounds weight respectively, and sufficient light to note the varieties in the class of coal sampled. The following method is recommended:— 1. Preliminary.—Cut a channel about 2 ft. wide and 3 to 4 inches deep at right angles to the footwall so as to remove the surface coal which has been exposed to atmospheric action, and also to give a clean surface from which accurate observations of the face of the seam can be made. 2. Sampling from the Top.—Lay down the sheet and start picking at the top of the seam, cutting out a channel 2| to 4 inches wide and 1| in. deep. Should a larger piece fall, mark it, break off and discard the excess quantity, only taking into the sample that quantity which would have been picked down to form a channel of uniform size. 3. Sampling from the Bottom.—Lay down the sheet and start picking at the bottom of the seam, cutting out a channel as above and then continuing as in 2. Should * fines ” collect on the face, they should be brushed off. Under no circumstances is it permissible to use water for this purpose. A broad flat brush, such as is used for whitewashing, has been found satisfactory. 4. General.—The sampling should be stopped at partings or changes in the nature of the coal; then all the coal on the sheet should be put into a bag with printed number tickets (such as are found in duplicate number books) and registered in the sample book, with description of coal, width of coal sampled, width of parting or band, nature of parting, and exclusion or otherwise of parting or band from the total sample. Again lay down the sheet and continue the sampling until the next change is noted, and then register as above, stating that this is the second sample from the top. The remainder of the seam is sampled in the same way. In order to arrive at a true average of the seam, all these samples must be dealt with separately and analysed separately. If a large body of the same class of coal occurs in the seam, it may with advantage be split up into sections when being sampled. 2.—Sampling a Ship’s Cargo. The method of sampling is dependent on the manner of unloading, and, as sampling is in this case a difficult and very laborious operation, the following method should be used only when it is desired to obtain accurate samples of the whole cargo. In the absence of a mechanical system of discharging, the coal is removed from the holds by labourers in small quantities in baskets or other receptacles. Every hundredth receptacle should be emptied out completely on to a clean non- absorbent floor, preferably of steel plate ^in. thick, or cement, or into a special hopper leading to the above, the floor being protected by a shed. The large lumps in this sample are broken on the floor, the whole is completely mixed, collected into a conical heap and then quartered, taking care that all the fines, &c., of the rejected diagonally - opposite quarters are totally removed, and returned to the original consignment. Since by this method it is possible to handle only small quantities at a time, the sampling of the remainder should be carried out simultaneously in an adjacent portion of the shed in a similar manner. The results of all the quarterings are finally mixed together and quartered down until about 4 tons remain. This is crushed to pass through 3in. round holes, when it is coned and quartered twice, leaving a reduced sample of about 1 ton. This sample is then crushed to pass in. holes, when it is coned and quartered twice, leaving a reduced sample of about 500 lb., which is then crushed inside. During the reduction of any sample great care must be taken to keep the sample free from any foreign material such as water, other coal, ash or dirt, and the crushing must be carried out in a place entirely free from draughts. 4,—Truck Sampling. A.—Truck Loading. 1. From Chute.—The samples must be taken at regular intervals of time by holding a shovel under the loading chute and then putting the shovelful on to a sampling floor or into a bag. A sample of not less than 200 lb. should be obtained by the time that the truck is fully loaded. The quartering, &c., of the sample is then as prescribed for other methods. 2. From Platform.—If the truck be loaded from a platform a shovelful should be laid aside at regulated intervals, e.g., every fortieth shovelful, until a sample of not less than 200 lb. has been obtained, which is then reduced as prescribed. If possible, however, sample the truck being loaded as if it were bunker coal, taking the sample five times during the loading—namely, when the truck is ready to be loaded, then when it is quarter full, when half full, when three-quarters full, and when almost full. B. —Truck in Transit. Sampling coal in a truck in transit to obtain an average sample of its contents is undesirable and not to be recommended, but, where inevitable, great care must be exercised. The sample should be a large one—not less than 200 lb. weight. C. —Truck Unloading. The truck is divided equally down its entire length and one half removed, leaving the other half intact as far as possible and a section of the contents thus exposed is sampled with a shovel, but at one-fourth its depth from the upper surface and one-fourth its depth from the bottom. By taking coal at these levels every 3 ft., starting at one end and taking in this way a weight of not less than 200 lb., the inclusion of weathered coal is avoided as far as possible, and any accumulation of “ fines ” at the bottom of the coal in the truck due to travelling and handling is also avoided. The reduction is the same as prescribed for other methods. D.—Hopper Truck. On account of the bottom discharge by gravitation and the inclination of ends and sides, the sampling in this case becomes a most difficult operation, and, from the point of view of accuracy, is the most inadvisable of the methods of truck sampling. The sampling, therefore, should be done by several persons, say four. This should be commenced only when the doors are fully opened, since the period occupied in opening the doors allows time for the small coal, &c., produced by the fall on to the steel plates, when loading is commenced, to be discharged before the average contents, which it is desired to sample, make their appearance. The actual sampling is carried out by each sampler taking a shovelful as rapidly as possible at points about one-third the length of the truck from each end, in order to avoid “ fines ” from end inclines. It should cease before the last portions of the coal are discharged, while the doorways are still covered with coal and before the “ fines ” begin to fall. By this time a sample of not less than 200 lb. should have been collected, which is then quartered, &c., as prescribed. 5.—Bag Sampling. Sampling coal contained in bags without emptying them is unsatisfactory, and should only be resorted to when it is impossible to sample the coal in bulk. If time and space permit, empty out the selected bags on to a clean and suitable floor and treat as formerly until the final quarterings yield a sample of not less than 200 lb. weight. 6—Laboratory Treatment of Coal Sample. As a suitable receptacle for conveyance of the sample to the laboratory on the high veld, it has been found that bags made of a duck canvas of good quality which can be closed tightly by string or strong tape, are satisfactory. If these cannot be obtained it is preferable to use an airtight tin with a screw or other close-fitting stopper, which can be sealed with adhesive tape such as is used by electricians, so that the sample, when received at the laboratory, will be in the same condition as when sealed up. The sample should be properly labelled, and during transmission to the laboratory must be kept dry and not exposed to the sun or any artificial heat whatsoever. When received at the laboratory it should be dealt with as soon as possible after delivery. It has been found by experiment that samples of coal crushed to T5K in. cubes as prepared for a laboratory may be kept for two months in canvas bags of good quality at the usual laboratory temperature, closely secured so as to prevent air circulation, and kept in a cupboard or otherwise protected from continuous exposure to light.