694 THE COLLIERY GUARDIAN. April 5, 1918. 3. If necessary (on account of lack of space) to store “through” coal or mixed smalls to a greater height than 13 ft., these should be laid down in succeeding layers of not more than 3 ft. to 4 ft. thick. These heaps should also be provided with perforated ventilation pipes, from 3 in. to 4 in. in diameter. Iron or earthen- ware pipes may be used—a pipe to every 300 sq. ft. of surface. The lower ends of these pipes should be at different heights from the ground throughout the stacks. 4. A thermometer should be lowered occasionally through the pipes to ascertain the temperature at various depths of the stack. 5. Never stack coal behind wood structures, on moist vegetable soils, or on ground covered by coarse vegeta- tion, like brackens. 6. Do not mix inferior (dirty) coals with the better class varieties; and remove as far as possible all “ rashings ” or other friable bituminous shale bands before storing. 7. Never allow coking coals to be stored in heaps of more than 4 ft., and only for short periods, as very slight heating renders them useless for coke-making. 8. Wet small coal should not be mixed with the dry coal. It may be dumped around the edges of the stack, where the air can get to it freely. CANADIAN COAL AND COKE OUTPUT IN 1917. According to the preliminary report by Mr. John McLeish, the total production of marketable coal in Canada during 1917 (comprising sales and shipments, colliery consumption, and coal used in making coke or used otherwise by colliery operators) was less than the 1916 production by 467,807 tons, or 3'2 per cent, in quantity, but greater in total value by 8,826,165 dols., or 22'7 per cent. Production, imports and exports, and consumption during 1916 and 1917 were as follow:— 1916. 1917. Short Value. Short Value, tons. Dois. tons. Dois. Production ... 14,483,395... 38,817,481... 14,015,588... 47,643,646 Exports .... 2,135,359... 7,099,387... 1,733,156... 7,387,192 Imports .... 17,580,603... 38,289,666... 20,857,460... 70,562,357 Consumption 29,928,139... — .. 33,139,892... — The exports fell off by 402,203 tons, or 18'8 per cent., the imports were increased by 3,276,857 tons, or 18'6 per cent. The apparent consumption increased by 3,211,253 tons, or 10'7 per cent. The total output of coal, including waste and unmarketable slack, was, in 1917, 14,411,011 tons, as against 14,815,703 tons in 1916. The 1917 production included 108 225 tons of anthra- cite (all from one mine in Alberta), 11,135,095 tons of bituminous coal, and 2,772,268 tons of lignite coal. The provinces of New Brunswick, Saskatchewan, Alberta, and the Yukon made greater production of coal during 1917, and with the exception of the Yukon, show the highest annual production on record. The total increase in these provinces was 284,781 tons. The total decrease in Nova Scotia and British Columbia was 752,588 tons, leaving a net decrease as already shown. The Nova Scotia production fell off 587,456 tons, or 8'5 per cent., as compared with 1916; New Brunswick increased 45.120 tons, or 314 per cent.; Saskatchewan increased 74,004 tons, or 26'3 per cent.; Alberta increased 164,085 tons, or 3 6 per cent., notwithstanding the serious loss of output due to strikes; the British Columbia production fell off 165,132 tons, or 6'4 per DAILY COST SHEETS FOR MINE MANAGERS. By E. B. Wilson. Well systematised collieries, under normal condi- tions, run with the smoothness and precision of well- managed factories. In each case, under the most capable supervision, slight derangements will occur from time to time, but these, however, the capable manager will reduce to a minimum. Good coal mine managers attain their attributes by studying all phases of the business, and analysing the methods followed in the different departments. The executive ability attained in this manner must carry with it a certain amount of humanity and diplomacy, otherwise an exceedingly valuable attribute is wanting. The coal mine manager must systematise the details of the various operations in order that he may keep his fingers on their pulse, and not be too dependent on subordinates for information. Among the affairs that the manager should follow closely is the financial condition of the operation, and to this end he should have daily cost sheets that will cover the entire plant. In coal mining, the principal items debited to production are labour, supplies, build- ings, office expenses, and, where the land is leased, royalty. The items credited to production are tons of coal shipped at a stated price, f.o.b. tipple, rents, and miscellaneous sales of supplies to the employees. The debits may be divided and subdivided under numerous headings in order to know just what each item entering into- the cost of production totals, but this report requires considerable labour, and is of no particular value daily, although as a check on the ability of foremen, and as a means of comparison, it might be of some use if compiled weekly. Under normal coal mining conditions, company labour charges remain fairly constant, and if there is to be an abnormal increase, the manager and foreman are to consult; the former is the responsible head of affairs, and the latter should not assume the respon- sibility of materially increasing the cost of production in his department. Whilst labour is the most expensive item in colliery operation, as stated, it fluctuates but slightly under normal conditions, whereas expenditures in other items are extremely variable. Therefore, if the manager is wise, he will make use of a daily cost sheet. One method of arriving at the daily cost of produc- tion is to aggregate separately the daily expenditures and receipts, and then divide the former by the latter. This ratio between the expenditure and receipts gives the practical cost of production, even though the pur- chases may not be used for several months or extend into the following year ; and while it may not represent the actual cost of mining for any one month, it shows the manager the financial condition of the enterprise, which is of as much importance. The wise manager anticipates lean times as well as fat times, and pro- vides working ammunition for the former. To the general run of shareholders, a cash balance is more pleasing than an inventory balance when ship- ments are small; and it should be to the manager. While most managers have daily reports showing the financial condition of the plant, for those who have not, the simple forms illustrated may be used as a guide. SEPARATING MATERIALS OF DIFFERENT SPECIFIC GRAVITIES.* By T. M. Chance. All gravity methods for the separation of ore from gangue, or of slate and other refuse from coal, are based upon differences in the falling velocities, in some fluid medium such as air or wTater, of the materials to be separated. As all materials falling in a vacuum have the same velocity, independent of the size, shape, weight or specific gravity of their individual particles, it would be more accurate to describe the operation of these methods as depending upon the retardation of falling velocities effected by the resistance of a fluid medium, this retardation being greater for small or light particles than for large or heavy particles. This generalisation is true also of those appliances utilising centrifugal force to replace or to supplement the action of gravity. The separation of materials of different specific gravities by means of a fluid having a specific gravity greater than that of the lighter particles and less than that of the heavier particles has not been applied com- mercially, or on a large scale, to the separation of ores or to the washing of coal, the method being limited to laboratory experimental work or to laboratory deter- minations for the purpose of checking up the work of jigs, classifiers, and other types of concentrating appliances. A solution of zinc chloride has thus come into general use in the laboratory to separate coal, bony coal and slate, both to check up the work of coal- washing plants and for the purpose of making tests preliminary to the designing of coal-washing plants. The use of a heavy solution of some chemical in water has often been proposed for making such separations, especially in connection with the washing or preparation of coal. Practically insuperable difficulties, however, have prevented the commercial development of any such process, the difficulties being both physical and financial. The cost of the chemical used to make high- gravity solutions is usually prohibitive, and the freeing of the coal from all traces of the chemical is found to be practically impossible. Such solutions inevitably penetrate the individual lumps and particles of coal, transfusing into the pores and saturating the joint- planes, and very large quantities of wash water would be required to free the prepared product from the chemical with which it was thus contaminated. The use of large quantities of wash water renders it practi- cally impossible to recover the chemical for subsequent use at a reasonable cost, because this requires concen- tration by evaporation of the wash water. The method now to be described is based upon the facts that any relatively finely comminuted insoluble solid matter (such as sands), if mixed with a certain quantity of liquid (such as water), can be maintained suspended in the liquid by continuous agitation, and that the mixture, so longas agitation is maintained, will form a mass exhibiting physical properties similar in every respect to those of a fluid of relatively high specific gravity, including its ability to float solid bodies having less specific gravity, while permitting solid bodies of greater specific gravity to sink in it. The agitation of such a fluid mass may be effected and maintained by any suitable mechanical appliances, or by introducing liquid under pressure into the fluid mass, either as jets or as a slowly rising current. When a fluid mass of a certain predetermined specific gravity has been produced in this manner, its specific gravity will remain constant so long as the agitation applied to it is not varied. The specific gravity of the fluid mass will be diminished by increasing the agitation (provided the Form 1. DAILY EXPENDITURES. DAILY RECEIPTS. Date. Store. Shop.* Mine. Stable. Powder. Build- ings. Outside Labour. Inside Labour. Fixed Charges. Total. Store. Shop. Powd r. 1 | Coal. 1 i 1 Build- ings- Total. Daily Cost. Cost to Date. Yearly Cost. Form 2. DAY BOOK LEDGER TRIAL BALANCE SHEET. Consignor. Date Recd. Date Paid. Discount. Store. Supp y House. Mines. Shops. Bldgs. Stable. Credits. Debits. P. &L. Dr. P.&L. cent.; the Yukon production, though small, shows a large percentage increase. The total imports in 1917 included 15,537,262 tons of bituminous coal, valued at 42,452.771 dols., or an average of 2'72 dols. per ton, as against 13,009,788 tons, valued at 17,073,303 dols., or an average of 1'24 dols. in 1916, showing an increase in 1917 of 2,527,474 tons, or 19'4 per cent.; and 5,320,198 tons of anthracite, valued at 28,109,586 dols., or an average of 5 28 dols. per ton, as against 4,570,815 tons, valued at 22,216,363 dols., or an average of 4 86 dols. in 1916, an increase in 1917 of 749,383 tons, or 14 1 per cent. A Plea for Committees.—Speaking at the annual meet- ing of the United Collieries Limited, in Glasgow, last week, Mr. Montagu S. Maclean, the chairman, referred to Government control, and said that those responsible for the conduct of the collieries were fast being reduced to mere nonentities. He pleaded for a better understanding between masters and men, based on the fundamental idea that their interests are in reality identical, and that com- mittees should be established on the lines of the Whitley Report to settle or anticipate minor difficulties and troubles, and let them try to mitigate the monopoly of labour by encouraging individual enterprise. Form 1, when bound in a book, will be helpful to those who wish to follow the daily cost of mining as well as the monthly. It can also be extended to show the average cost for every day in the year. The items for the sheet are readily obtained from the day-book and pay-roll; thus no additional work is entailed, and the sheet may be handed to the manager early in the morning before he takes up his routine work. In addi- tion to being a cost sheet, it affords the manager a means of keeping in touch with the expenditures in the various departments, and enables him to anticipate needed material. Under the heading “ Fixed charges,” office and store salaries, taxes, insurance, etc., are lumped. Inside labour includes the price paid for coal per ton or car, together with wages of company hands. It is expected that shop and building credits will vary slightly. Form 2 will also be found helpful. The simple arrangement combines day-book, ledger, bill-book, and, in connection with Form 1, a trial balance-sheet. This simple form of book-keeping saves time both for the manager and the book-keeper. In addition, the manager knows each day what vouchers he should sign or what cheques he should send out in order to take advantage of discounts.—Coal Age. necessary additional liquid is supplied for dilution of the fluid mass); while its specific gravity will be increased if the agitation be diminished. It is found that a mixture of sand and water can be used to produce a fluid mass having a specific gravity suitable for the separatian of coal from bony coal, slate, fireclay, pyrites and other impurities. The author has used sand ranging from 20 or 30 mesh down to 100 or 200 mesh, or even finer, and finds that fluid masses with specific gravities ranging from 1'20 to 1'75 are easily produced and can be maintained constant for an indefinite period at any desired gravity within these limits. The agitation may be effected by stirring arms, by propeller blades, by rotating discs and cones, by hydraulic jets, by upwardly-rising liquid, or by com- binations of hydraulic and mechanical agitation. In short, a very wide range of appliances can be used to produce the desired result. Moreover, fluid masses with a specific gravity high enough to float quartz, feldspar, limestone and other rocks, can readily be produced by using magnetic iron- ore sand and water instead of quartz sand and water. Other heavy materials can be used, such as ore con- centrates of galena, metallic copper, etc., for producing fluid masses having very high specific gravities. For the practical separation of materials of different specific gravities by this method, the following observations are evident:— 1. Every particle of material having lower specific gravity than that of the fluid mass will float; that is, the separation will be independent of the size of the materials to be separated. If the fluid mass be contained in a receptacle large enough to permit the introduction of large lumps, it is possible to dump into it the ore or coal, as mined, without any preliminary sizing, where- *From a paper read before the American Institute of Mining Engineers.