3116 THE COLLIERY GUARDIAN. May 30, 1913. the latter, the Sprengel water vacuum pump worked off the main supply has been found to give a reduction in pressure equal to about 725 mm., and to be in every way satisfactory. The employment of the apparatus is as follows:— In the dry weighed flask a quantity of the finely divided coal (80-mesh) is placed, and the weight of the same determined by difference; this flask is connected to the weighed U tube, whose limb nearest the flask is filled with lump quicklime, while that more remote is filled with finely-ground quicklime; this U tube is connected to the sulphuric acid drying tube, which is itself joined up to the Sprengel pump with an inter- Plug Plugs Fig. 5.—Apparatus for Determination of Water in Coal. vening tap. The pump is started and a vacuum gradually created (.the speed of the outcoming gas being shown by the bubbles in the sulphuric acid drying tube), the flow of water through the pump is gradually increased, until a vacuum of about 700 mm. is created, then boiling water is poured into the beaker in which the flask containing the coal is standing, while to the beaker in which the lime tube is situated, a boiling aqueous solution of either sodium chloride or calcium chloride is added, care being taken that the corks of the tube are not wetted with the solution. The reactions taking place are as follows:— Under the reduction of pressure and at the tempera- ture of the boiling water surrounding the flask contain- ing the coal, the water in the coal, together with volatile matter varying with the nature of the coal, distil off and pass into the lime tube where, in accordance with the following equation CaO + H2O = Ca (OH)2, the water originally in the coal is chemically retained, while the other volatile matter from the coal, owing to the absence of any chemical affinity for the lime, and the higher temperature of the lime tube (due to its being surrounded by a boiling aqueous solution of sodium chloride or calcium chloride), passes through to the sulphuric acid drying tube, where some of it is retained, discolouring the sulphuric acid, while other portions pass through to the pump. At the end of about half an hour, the whole of the water having passed from the coal to the lime tube, the tap adjoining the vacuum pump is turned off, the beaker of boiling water surrounding the coal flask is removed and the air gradually let back through the sulphuric acid drying tube into the apparatus ; then the apparatus is taken to pieces,the lime tube washed, wiped, placed in a desiccator to cool, then weighed, the increase in weight noted (this increase is solely due to water from the coal) and the percentage of water in the coal calculated. Accuracy of the Method. It will be remembered that the sources of error in the simple drying method for determining the percentage of moisture in coal are:— (a) Oxidation of pyrites making the result too low; (b) Oxidation of the coal itself making the result too high; , (c) Volatilisation of matter contained in the coal making the result too high. In the new method, the two errors due to oxidation no longer exist, because the water is distilled from the coal in the absence of air, and consequently no oxidation can take place. With regard to the error due to volatilisa- tion of matter in the coal, something more must be said, for this volatilisation still takes place, but, since the temperature of the quicklime tube is higher than the coal itself, no condensation can take place in this tube unless chemical action takes place. Though these errors of the simple drying method are removed, it is possible that fresh errors have been intro- duced, consequently some consideration of this possi- bility should be given. The possible sources of error may be divided into two classes—namely, chemical and physical. Considering the former, the question has to be asked, “Does the coal under the reduction of pressure give off any matter besides water which has a chemical affinity for quicklime ? ” The first answer that occurs to one is, “ Yes, the coal probably gives off carbon dioxide which is occluded in ithowever, the author has examined a number of coals by putting them under reduced pressure and passing the outcoming gas through baryta water, but so far he has failed to find the slightest trace of carbon dioxide by this extremely delicate test. gas. Another possible product from the coal is phenol In conclusion, the author would like to express his (C6H5(OH)); however, on removing the lime from the thanks to Prof. Carlyle, for allowing him the use of the drying tube after the determination of the moisture in laboratory of the Royal School of Mines, and to Prof, various coals, the ordinary test has always indicated the Merrett for the kindly interest he has taken in the absence of phenol. compilation of this paper. Turning to physical errors, one undoubtedly exists, for the lime tube is attacked with loss in weight by the boiling solution of calcium chloride, and therefore for the most accurate work a correction must be applied, which is dependent on the strength of the calcium chloride solution and the time of immersion; in the case of the solution employed by the author it was found that the drying tube lost in weight 0 0030 gm. per hour. The following table of results of three representative coals examined, shows that the results are independent of the time that the coal is under the influence of heat and reduction of pressure. Na f are of Coal. Weight of Coal. Apparent Increase in weight of Ce.O Tube. Time. Correction.! True Weight of 1 Vv ater. | Water. gm. gm. min. i gm. % 9’4305 0-2600 30 + 00015 0’2615 2-77\ Anthracite. 5-2244 0-1427 30 +0-0015 0-1442 2-7712-78 3-1360 0-0860 30 + 0’0015 00875 2-79, 4-0800 0-2618 45 + 00022 0 2640 6-461 Bituminous. < e Jr6’45 4-3442 0-2784 30 +0-0015 0-2799 6’44) 10-4042 1-0588 60 + 0-0030 10618 10-211 Lignite | 3-7666 0’3832. 30 | +00015 0-3347 10’21 10-20 1 8-2526 0’8390 30 j +0-0015 ' 0’8405 1019 Before ending this communication, the author feels that, in referring to one other matter, he will not be going outside the scope of this paper if he draws atten- tion to a fact found out by him in the course of the investigation, but having no significance with regard to the two methods of determining moisture ijti coal which have been discussed. When determining the percentage of moisture in an anthracite, it was found that the increase in weight of the drying tube was greater than the loss in weight of the anthracite in the coal flask by an amount far greater than would be accounted for by the fact that the aqueous vapour in the air originally in the apparatus would be absorbed by the drying tube; naturally it was at first supposed that there must be some leak in the apparatus between the coal flask and the drying tube, but this, on performing a blank experiment, was not found to be the case. The experiment was repeated, using anthracite in the coal flask, and it was found that, while the increase in weight of the drying tube was equal to 2*78 per cent, of the anthracite employed, the decrease in the weight of the anthracite in the flask was equal to 2’52 per cent. So striking was this result that this experiment was repeated ten times in all, when it was found that the mean increase in weight of the drying tube was equal to 2’78 per cent, of the anthracite employed (these results did not differ by more than 0*04 per cent.), while the Analysis : Ash, 14’00 % ; ’Sulphur, 2’65 % ; Coke, 88’0 % ; WateY, "2-78 % ; Cal. Power, 10’1. Fig. 6.—Anthracite: Drying in Vacuo at 100° C. 2-3 2 7 io True Percent me H?O 30 ao - 2 9 2 5 « 2'78 50 MIN Ch mean decrease in weight of the anthracite in the coal flask was equal to 2’54 per cent.; however, these results differed from one another by as much as 0'17 per cent., but no result was higher than 2’62 per cent. This curious state of affairs is illustrated in fig. 6, where the percentage loss in weight is recorded on a time base; from this it will be seen that the loss in weight of the anthracite at the end of 30 minutes was 2>’52 per cent., and that it remained constant at this figure. This curious fact having been undoubtedly established, the author sought for some explanation of it, and could but conclude that when the water left the coal under the influence of the reduced pressure and heat, it left it in the physical condition of charcoal, capable, like charcoal, of absorbing many times its own volume of THE NEW MINES ACT : CONFERENCE ON GENERAL REGULATIONS. Conferee ces Concluded. The joint conference of representatives of the coalowners and miners of Great Britain on the draft regulations issued by the Home Office for the administration of the new Coal Mines Act was concluded at the Westminster Palace Hotel, London, on Friday last. Mr. F. J. Jones, Yorkshire, chair- man of the Mining Association, presided, and Mr. R. Smillie, president of the Miners' Federation, was in the vice-chair. At the conclusion of the meeting, the Secretaries (Sir Thos. Ratcliffe-Ellis and Mr. Thos. Ashton) stated that the whole of the amendments submitted to the Home Office by the Mining Association and by the Miners' Federation had been considered, and that an agreement had been reached on a number of the amendments, but on others they had disagreed. The points which were in dispute would have to be decided by the referee appointed under section 117 of the Act. It had been arranged that the representatives of the coalowners and miners should attend at the Home Office on June 3 to report to the Home Secretary the results of the conference and the rules on which there had been an agreement. ___________________________ Geological Research in the Coalfields.—According to the reports for 1912 on the Geological Survey, the Geological Museum, &c., field work in England and Wales has continued in the Denbighshire district, the Warwickshire and Stafford- shire district, and the London and South-eastern district. In the first of these areas progress has been made in the surveying of the Flintshire coalfield. There appears to be reason to suspect that the productive measures are uncon- formably overlain near Flint by some barren red strata of late carboniferous age, and that much of the productive measures may be locally absent. In Scotland the original survey has been continued in Mull and in parts of Suther- landshire, Perthshire, Invernessshire and Argyllshire. In the Island of Mull information has been collected with reference to the tertiary coalseams and the occurrence of iron in the igneous rocks. The 6 in. maps of the Lanark- shire coalfield (central portion) are being prepared for publication. Work is now being carried forward in South Lanarkshire and North Ayrshire. The information now being collected will, it is stated, greatly increase the accuracy of future estimates of our coal resources and the life of tbe respective coalfields. A beginning has been made with the task of correlating the seams in the Ayrshire and Lanarkshire fields. The memoir on the concealed coalfield of Yorkshire and Nottinghamshire is in the Press. In the Jermyn-street museum a temporary exhibit has been prepared to illustrate the memoir on the mesozoic rocks in some of the coal explorations in Kent. Checking Underground Workmen.—A meeting of the North Staffordshire branch of the National Association of Colliery Managers was held on Monday at the North Stafford Hotel, Stoke-on-Trent, Mr. A. M. Henshaw pre- siding. A discussion took place on the question of checking underground workmen, two systems being described in detail by Mr. M. B. Gardner and Mr. A. Marshall respec- tively. In the method described by the former, two sets of checks are used. The workman is supplied with a circular check on being set on, and in exchange for this receives his lamp and a hexagonal check. At the pit bottom the fireman examines the lamp and receives the hexagonal check from the workman. Both in the lamproom and at the pit bottom the checks are placed on boards and the numbers entered on registers. At the close of the shift the man claims his hexagonal check at the pit bottom and returns it with his lamp to the lamphouse, where he receives his circular check again in exchange. The boards show what men are below ground, and at the close of the shift indicate any man who may not have come out of the pit. In the system explained by Mr. Marshall one set of checks is used. The workman receives his lamp and a check bearing the same number as the lamp and proceeds to his fireman at the pithead. There the lamp is examined and the check placed on a board, one being provided for each seam. From these boards a record is taken, and the lampman also makes a list of the numbers and names of the men whose lamps have not been taken out. On returning to the surface each man takes his own check from the board and returns it with the lamp to the lamproom. The boards show who is in the pit and where the men are working.