The Value of Various Descriptions of Wood for Pit Timber. C. DÜTTING. (Glückauf, 8th October, 1898, p. 797.) Comprehensive experiments have been for some time past in progress in the Government Collieries at Saarbrücken, to test the utility of various kinds of timber for employment in mines. One reason for undertaking these tests was the steady diminution in the use of beechwood for these purposes, notwithstanding the fact that the mines in question are situated in the midst of splendid beech forests. The principal objects in view were to ascertain the respective value of beechwood props and of acacia wood props, and to determine whether any of the known processes of timber preservation could be employed with advantage in the case of these woods. It is observed that there has recently been a great reduction in the price of fir timber, which may to some extent have prejudiced the employment of beechwood. The price of fir is, however, now rising, and inquiries are being made for cheaper descriptions of wood. In these collieries a sum approaching three millions of money has been expended upon timber alone during the 21 years ending 1895, and thus any saving in the matter of the outlay upon wood is important. The descriptions of timber used in the experiments were as follows: beech, oak, fir, and pine. In lieu of conducting the tests in the usual way with small cubes of sound wood, it was decided to use the props entire, as sent to the pits in lengths of from 3 feet to 8 feet. Five sets of tests were made with each description of timber and the results are given in Tables. The beech samples in each case were superior to the other descriptions of timber. The props were exposed to weather above ground and in the pit, and were tested in various ways, and the Author states that the objections which have been urged against beechwood were not sustained, whereas the excellence of oak timbering for use in the pit has apparently been overrated. Corresponding experiments were made with the wood of the acacia (Robinia pseudo-acacia), which is said to flourish well on poor soil and to send up shoots from the rootstock, which in about 15 to 20 years attain proper proportions for pit-props. It has been asserted that this timber surpasses oak in strength and durability. The acacia gave favourable results under these tests, but its weight and its relative costliness would militate against its employment. Its growth on suitable soil would seem to be. extremely rapid. In conclusion, reference is made to certain preservative solutions, which have been proposed for increasing the durability of pit timber, but these trials are not yet complete. G. R. R. [THE INST. C.E. VOL. CXXXV.] 2 E Coals of the Basin of the Donetz. Captain KHUDINTZOV. (Morskoi Sbornik, November, 1898, non-official past p. 137.) Cardiff coals for the Black Sea fleet were superseded 10 years ago by coals from the Donetz basin, and in 1897 the first contract was made for the supply of these coals to the Baltic fleet. This coalfield extends over a large portion of New Russia, from the Don to the Dnieper. Ordinary coals are found in the western part and anthracite in the eastern part of the district; the change from one to the other taking place gradually, so that a great variety of coals is found. The Author gives a short account of the development of the coal industry. Peter the Great is said to have initiated it in the early part of the last century. Systematic search for coals was commenced in 1735, and in 1740 the result of the first geological survey, under the direction of a Frenchman, Le Plé, was published. Working coals now commenced and increased rapidly. In 1798 the first iron foundry was started at Lugansk. Deficient transport prevented the development of the mining industry till, in 1864, the railway was opened from the Grushevka anthracite mines to Rostov; and in 1870, the KurskKharkov-Asov railway, to serve the western part of the coalfield. Since then the output has continued with increasing rapidity. A diagram is given showing this rapid increase, from 60,000 wagons in 1880 to 430,000 in 1897, each wagon containing 600 poods (9.67 tons). In 1830 shafts were sunk for the first time, previous to that workings had all been from the surface only. The Author tabulates the ordinary coals in five groups, according to quality and composition; the lowest quality having a specific gravity of 1.25 and 75 to 80 per cent. of carbon, and the highest a specific gravity of 1.35 to 1·4 and 90 to 93 per cent. of carbon. Besides these there is the anthracite with a specific gravity of 1·4 to 1.8 and 93 to 95 per cent. of carbon. The Author deals very fully with the question of analysing coals, and insists on the necessity of systematic analyses being made at the pit in order to sort the coals. into qualities suitable for different industrial purposes. He explains at length the methods adopted by the Government analysts for securing correct samples of coals, and for conducting the analyses. He then gives Table I of the results of analyses of coals for moisture, volatile products, ashes and sulphur, of forty-six samples of coals, by Prof. Alexeev, in 1897. This is followed by Table II, giving fifteen complete analyses, conducted at the Sevastopol Chemical Laboratory, of coals delivered into that port during 3 months of 1897, and some deductions from these two Tables. C. H. M. Separation of Ores by Magnetism. Dr. H. WEDDING, Government Inspector of Mines. (Verhandlungen des Vereins zur Beförderung des Gewerbfleisses, 1898, p. 263.) In a Paper of twenty-four pages with two sheets of illustrations, the Author, after describing the force and action of magnetism, refers to the attention lately devoted to the above subject and how this process is gradually supplanting the older ones. Magnetism, he points out, is applicable to the treatment of magnetic iron ores, such as apatite; calcined ores, viz., spathic iron and its compounds. Specular copper ore, sulphuret of zinc, calcium and galena, are by the same force separable from iron ores, and red and brown hematite, and native spathic iron from each other and from their compounds. Permanent magnets are applicable in the first two instances, while electro-magnets may be used in all, and must be in the fourth case. The magnets are in some instances protected by sheets of zinc or copper. Permanent magnets and electro-magnets are variously employed. The arrangements and processes at present in use are accurately described, and sufficiently illustrated to give a complete idea of the machines invented by Beuther, Busse and Seloe, W. von Siemens, Reed, Kessler, Edison, Max Putzig, and Siemens and Halske. The Author further gives the results of numerous experiments actually made with iron, zinc and other ores, and concludes with the remark: "That though there are innumerable questions still to be solved, yet the results already obtained are certainly calculated to provide purer iron, and to lead also to the reopening of abandoned workings, and the wider extension of iron-producing industries throughout the world." W. A. B. The Use of Blast-Furnace Gases in Gas-Engines. (La Revue Technique, 10th October, 1898, p. 437.) At the instance of Mr. Greiner, the general manager of the Société Cockerill at Liége, the Author has been engaged for some time past in studying the use of the furnace gases from the company's ironworks for gas-motor purposes. It was decided to submit the engine under trial to a 24 hours' continuous test, doing its normal work at a rate of 90 per cent. of possible explosions. The engine in question was of the "Simplex" type, and was constructed at the Cockerill works. The cylinder was 31 inches in diameter, stroke 39 3 inches. The engine made 105 revolutions per minute, and was of 200 HP. nominal. The gas was taken from the furnaces, without any special treatment, either direct or through a small gasometer, containing 10,700 cubic feet. The power developed was tested by means of a brake. A Crosby indicator was used to take the diagrams and to calculate the indicated work. The volume of gas used was determined by graduating the gasometer, and each of these volumetric trials lasted for 29 minutes, during which samples of the gas were withdrawn for the estimation of the calorimetric values. By means of barometric observations and temperature readings it was possible to reduce all the results to a mean atmospheric pressure of 30 inches and zero temperature respectively. The results are set forth in Tables, from which the following figures are extracted: mean consumption of gas hourly 21,362 cubic feet; mean effective HP. 181 16; use of gas per HP. hour 117.5 cubic feet. There was but little variation either in speed, effective HP., or in the calorific value of the gases during the experiment. The water employed was about 22 gallons per HP. hour, and the use of oil and grease was trifling. No troubles were caused in the cylinder by the dust from the furnaces and the gas-motor1 worked throughout as steadily as a steam-engine. G. R. R. On the Slag of the Basic Open-Hearth Furnace. O. THIEL. (Stahl und Eisen, 1898, p. 750.) The slag produced in the treatment of phosphoric pig-iron by the basic method in the open-hearth furnace is, under ordinary conditions, of small value for agricultural purposes, containing less phosphoric acid and more silica and iron than that of the basic converter-the last constituent in particular being due to the long duration of the final dephosphorizing period. This difficulty may be overcome when the Author's method of working the process in two furnaces is adopted-the proportion of lime or limestone added in the first furnace being kept below that required for perfect dephosphorizing, with the result of producing a slag high in phosphoric acid and silica, but comparatively free from iron which, in consequence of its composition, contains a high percentage of phosphoric acid soluble in citric acid as required for fertilizing purposes. The method has been adopted with a series of charges, the details of which are given. The pig-iron Two illustrations are given of this motor, together with an account of the experiments in La Nature, 15 October, 1898, p. 305. treated contains from 1.6 per cent. to 2 per cent. of phosphorus, which is reduced by the addition of 18 per cent. to 22 per cent. of limestone and 16 per cent. to 25 per cent. of ore (Swedish magnetite and pyrites residues) to between 0.25 per cent. and 0.70 per cent., while the resulting slag contains from 16 per cent. to 22 per cent. of phosphoric acid, 16 to 21 per cent. of silica, and only 4.68 per cent. to 7.68 per cent. of iron. In the second furnace, by a further addition of 9 per cent. of limestone, the steel is finished, giving a slag with 9 per cent. to 11 per cent. of phosphorus, but in much smaller quantity-the proportion of the first being 21.7 per cent., and that of the second 8 per cent., of the weight of the metal charged. By comparison with the results obtained in several establishments working the basic Bessemer process, it appears that for equal richness in phosphoric acid there is a larger production of slag with a smaller addition of lime in the open-hearth furnace than in the converter. This is due to the large loss of phosphorus by volatilization which in a hot blow may be as much as 30 per cent. or 40 per cent., as well as to the mechanical loss of lime carried away by the blast in the latter method. Comparing the quantity and value of the two kinds of slags, the Author considers that there is an advantage of between 18. 8d. to 38. per ton of finished steel in favour of the open-hearth method; and this may be largely increased by using the more phosphoric Swedish magnetites instead of the purer kinds in the first furnace. Thus with ore of 1.2 per cent. of phosphorus it would be from 38. 3d. to 48. 7d., and with 3 per cent. of phosphorus 68, to 78. 3d. per ton of steel better than with the basic Bessemer process, without taking into consideration the extra yield due to the reduced iron. H. B. An Improvement in Open-Hearth Steel-Making. (Stahl und Eisen, vol. xviii., 1898, p. 714.) At the Alexandrovski works in Southern Russia a modification of the Siemens ore process was introduced, in 1894, by Mr. Gorjainow. The ore, a hæmatite from Karnowatka containing Fe2O3 87 32 per cent., SiO2 7.70 per cent. and Al,O, 2.87 per cent., is mixed with 17 6 per cent. of dolomite and melted down in an open-hearth furnace, the mixture being easily fusible at about 500° or 600° C. Melted cast-iron is then run in, and a violent reaction takes place between the carbon of the metal and the oxygen of the ore, the effervescence being so great that the capacity of the furnace must be about four times that of an ordinary open-hearth furnace worked in the usual way. The operation is very much shortened, the charge being finished in 6 hours instead of 12 hours, and the consumption of scrap is considerably reduced. The furnace-bed is made of lumps of chromic |