268 THE COLLIERY GUARDIAN. February 11, 1916. CURRENT SCIENCE Calculation of Relative Humidity. In estimating the degree of humidity of the atmo- sphere from the readings of the hygrometer, it is customary to use hygrometric tables which show the saturated-vapour pressures at different temperatures. In the use of this method the actual vapour pressure for any degree of saturation or any dry-bulb reading is first found by dividing the difference of the two readings by a constant 88, multiplying the quotient by the ratio of the barometric reading to the average sea-level barometer (30 in.) and subtracting this product from the saturated- vapour pressure corresponding to the wet-bulb reading. This is expressed by the following formula :—■ Pv -Pw The relative humidity H is then found by multiplying the actual vapour pressure pv by 100 and dividing by the saturated-vapour pressure corresponding to the dry- bulb reading taken from the tables, as expressed by the formula TT = (2) Pa Applying these formulae to find the relative humidity in a case cited by a correspondent, and assuming a barometric pressure B = 30in., the saturated-vapour pressures corresponding to the dry and wet readings, as taken from the tables, are pv = 0’7335 and pw — 0’576, the corresponding temperatures being td = 70 degs. Fahr., and tlv = 63 degs. Fahr. For the actual vapour pressure we then have, from formula 1, f-=M76"“ (”»“)=M”-»= Then, applying formula 2 for the relative humidity, we have n- 100 x 0 4964 , H =--------= 67 per cent. 07335 1 No formula appears to have been published by which the percentage of humidity can be calculated directly from the wet- and dry-bulb readings of the hygrometer without reference to the tables previously mentioned. However, fairly approximate results can be obtained for sea-level readings by the use of the following formula, which requires a knowledge of logarithms, owing to the decimal exponent. In this formula the 0’84 power of the difference of the readings is divided by the dry-bulb reading, and the quotient obtained multiplied by the absolute zero of the Fahrenheit scale. The resulting product subtracted from 100 gives the percentage of moisture or the relative humidity of the air. Thus, (/ + ,(isi H = 100 — 460 (3) td Assuming sea-level observations (bar. 30 in.) and substituting the values previously given, tci = 70 degs. and tw = 63 degs., the relative humidity is H = 100 - 460 (7° ~ 63'08‘ = 66'3 per cent. 70 - Again, assuming a sea-level barometric pressure: of 30 in. and hygrometric readings, td = 65degs. and tw — 45 degs., and finding the relative humidity corre- sponding to these readings by formulas 1 and 2, since the corresponding saturated-vapour pressures taken from the tables are pd = 0’6176 and pw = 0’2995 in., for the actual vapour pressure is found by applying formula 1, to be ^ = 0'2995 - = 0'0733 in. The application of formula 2 gives the relative humidity, n 100 x0-0733 , H =• —— — 12 per cent., nearly. 0'6176 / J Finding the relative humidity in this case by the use of formula 3, as proposed, gives H = 100 — 460 ~~ 45) — 12 -p per cent. 65 The formula (3) given above is in no respect a rational formula, but has been derived by observation of hygro- metric tables, and gives a fairly close approximation to the percentages of humidity obtained by the use of the tables, while the calculation is much shorter. As stated previously, however, formula 3 can only be applied to sea-level observations.—Coal Age. Producer Clinker. Mr. H. F. Boughton (Gas World) says that of all the troubles in gas manufacture, the question of clinker formation in the producer appears to be one that has been left entirely to the mechanical side of engineering, whereas in the writer’s opinion it is purely a chemical matter. It is therefore strange why the chemist has so long neglected it. The combustion from C to CO and then from CO to C02 is an exothermic process, i.e., one in which heat is developed, whilst the reduction of C02 to CO is endothermic, i.e., heat is absorbed during the process. The lower zone of the producer charge therefore generates more heat than the upper. Nearly all kinds of gas coke will form clinker if the ash receives sufficient heat, and the amount of heat required depends upon the chemical constituents of the ash and the particular conditions under which heat is applied. Clinker will form quicker when the producer is fall of coke or has a thick bed than when shallow, and the frequent pricking of the bed near the bottom and through the bars will also hasten its formation. To avoid clinker the ashes should be burned, and not melted, bub this is impossible with most gas cokes on account of the melting temperature being so near the burning. The melting point of coke ash is higher in AND TECHNOLOGY. an exothermic zone than in an endothermic, therefore the ash formed in the middle section of the fuel bed is more easily converted into clinker than the ash nearer the grate. The mechanical means hitherto generally employed to assist in the avoidance of clinker formation has been to keep the under part of the furnace cool by means of water in a tundish situated in the ashpit, and by means of water dripping down inclined plates arranged above the grate in front of the furnace. The drip, however, is also for another purpose. In another method, pre-heated primary air passes over a covered trough containing water, and is supposed to collect wet steam which passes through the grate with the air into the fuel. Another plan has been to pass exhaust or Live steam up between the bars. This becomes superheated, partly decomposes, and it is assumed the absorption of heat for this purpose keeps the ashes below the melting point. No mechanical means hitherto adopted, however, ha^ proved entirely successful. Pre-heated primary air in most cases enhances clinker formation. The presence of clinker in the fuel bed at once reduces the efficiency of the producer, as it chokes up the free passage for air, and more has to be admitted in the exothermic zone than the actual amount required for the production of the correct producer gas. Seeing, there- fore, that the melting point of ash is lowest where CO is formed from C02, it will obviously be advisable to introduce into this zone a flux or substance which would still further reduce the melting point, and thereby cause the ash to melt to a less viscous condition in order to enable it to run down into the ashpit. A flux is a substance used to make the union of two metals under heat, and it performs this function by preventing the .oxidising of the parts in contact. If the oxidising of the metals in the ash could be avoided, the clinker would become fluid and flow down from the producer into the ashpit. There are three types of fluxes, viz., the acid, oxidising, and oxygen reduction, any or all of which could be experimented with. Lime- s:one broken or crushed to the size of potties if spread over the bars of the furnace will be found to reduce clinker formation .to a large extent, but, of course, it is not lasting. It is, however, up to the chemist to find a substance to mix with the charge in order to avoid all clinker making in the producer. It is claimed that step bars do- away entirely with clinkering, but they require a constant amount of atten- tion and frequent manipulation, and this may considerably deter the correct working of the heats. The less a fuel bed is disturbed, the better the producer will work, providing clinker does not form and so distort the section of the fuel bed. FATAL ACCIDENTS IN MINES AND QUARRIES DURING 1915. An advance proof (subject to correction) of the tables of fatal accidents and deaths in and about the mines and quarries of the United Kingdom, during the year 1915, has been issued by the Home Office. Under the Coal Mines Act :— T e_. X ca Separate fatal accidents— Scotland 8... 6... 38... 19... 6... 68... 23... 10... 74... 29... Northern .......... 1 . 115 .. York & North Midland 1...140... Lancashire, N. Wales and Ireland— Lancs &N. Wales 1... 74... 6... 43... 11... Ireland........... —... —... —... —... South Wales ......... 1...181... 15... 94... 26... Midland and Southern 4... 65... 6... 45... 18 135.. . 136 317": 368 138.. . 123 Totalin 1915 ... 16...649... 49...3-32 .126... 1,202... — Total in 1914 ... 10...580... 62 . 390 ..131... — ..1,182 Deaths— Scotland ........... 11... 75... 6... 38... 19... 149... 159 Northern................ 7 . 118... 6... 68... 24... 223... 199 York & North Midland 1.. .141... 18... 76 ... 30... 266... 219 Lancashire, N. Wales and Ireland— Lancs. & N. Wales 1... 75... 7... 43... 11... 137... 140 Ireland............ —... —... —... —... —... — — South Wales .............. 1...191... 15... 95... 26 328... 377 Midland and Southern 20... 66... 9... 72... 19... 186... 125 Total in 1915 ..... 41...666... 61...392 129...1,289... — Total in 1914 26...591... ( 5...396...132... — ...1,219 Of the deaths from falls of ground, 426 occurred at the working face, 134 on roads while repairing or enlarg- ing, and 106 on roads while otherwise working or passing. Of the deaths from shaft accidents, 8 were due tc overwinding, 1 to ropes or chains breaking, 16 occurred whilst descending or ascending by machinery, 2 by falling into shaft from surface, 14 from falling from part way down shafts, 2 to things falling into shaft from surface, 2 to things falling from part ■ way down, and 16 to miscellaneous causes. The deaths occurring from miscellaneous causes underground may be divided as follows :—By explosives, 18; suffocation by natural gases, 5; by underground fires, 14; irruptions of Water, 3 ; haulage, 265; ropes or chains breaking, 17; run over or crushed by trams or tubs, 217; other causes, 31; electricity, 8; machinery, 10; sundries, 69. Of the deaths on surface, 27 were caused by machinery, 61 by accidents on railways, sidings or tramways, 4 by electricity, and 37 by miscellaneous accidents. Under the Metalliferous Mines Act.—The following is a summary of the accidents and deaths under this Act : Separate fatal Deaths. accidents. Explosions of firedamp ........... nil nil Falls of ground ................... 6 ... 7 Shaft accidents .................. 2 ... 2 Miscellaneous underground .......... 6 ... 7 On surface ......................... 4 ... 4 Total, 1915 18 ... 20 Total, 1914 23 ... 24 Seven of the deaths were due to accidents by explosives. According to divisions, the deaths were as follows :— Scotland, 1; Northern, 8; Yorkshire and North Midland, 1; Midland and Southern, 10. Under the Quarries Act (in quarries over 20 ft. deep).— Similar details under the Quarries Act are also given : Place or cause. Separate fatal Deaths. Inside :— Falls of ground accidents. 21 23 By blasting 14 16 During descent or ascent . 1 - ... 1 Miscellaneous 22 22 Outside 12 12 Total, 1915 70 74 Total, 1914 ., 95 95 According to divisions the deaths were as under :— Scotland, 5; Northern, 6; Yorkshire and North Midland, 16; .Lancashire and North Wales, 18; Ireland, 1; South Wales, 4; Midland and Southern, 24. MANCHESTER GEOLOGICAL AND MINING SOCIETY. A meeting of this society was held on Tuesday last, under the presidency of Mr. Leonard R. Fletcher. The following gentlemen were nominated for election : Archibald Edward Jones, Neuadd, Forth, Glamorgan (federated); Harold Green, Brackley Colliery, Little Hulton, near Bolton; and Matthew Henry. Thorne, Vallonga, Portugal (associate members, federated). A paper on ‘‘ The Connections between the North- Western European Coal Fields ” was read by Prof. X. Stainier, Professor of Geology at the University of Ghent and Fellow of the Geological Survey of Belgium (see p. 263 of this issue). The President, in moving a vote of thanks to the professor, who was unable to be present, said the paper would no doubt prove a valuable one, and when members had had an opportunity of studying it, would lead to an interesting discussion. It was agreed to adjourn the discussion to a future meeting. The Coal Measures of the Croxteth Park Inlier. Geological Structure of the South Lancashire Coal Field. A discussion took place on two papers, “ The Coal Measures of the Croxteth Park Inlier ” and “ The Geo- logical Structure of the Somh Lancashire Coal Field,” read by Dr. Hickling, of the Manchester University, at a meeting of the Society on November 9, 1915 (Colliery Guardian, November 12 and 19). On that occasion, Sir Thomas Holland urged upon the mining community of Lancashire the advisability of arranging, on their own account, for a geological survey of the area affected by their mining operations. Mr. W. Ollerenshaw (Stockport), in a written con- tribution, said there could be no doubt in the minds of those who had studied the subject that Dr. Hickling’s paper would add a great deal to their knowledge of the Lancashire coal field. Whilst agreeing that further researches on the north, north-west, and south-western parts of the field would prove the author’s contention that the field extended under the Permian in some parts, he did not think there was any probability of an exten- sion being discovered on the north-east and south- easterly portions, the upheaval of the Pennine Chain having, in his opinion, broken the continuation of ;he coal field in that part of the county. He believed the south-easterly part of the Lancashire coal field would be found to lie in a basin-like trough, with its lowest part situated a few miles north-north-east of Manchester. He thought the conflicting opinions held regarding the conformation of the south-eastern district were due to the variation in the amount of dislocation or throw which was found in some of the principal faults intersecting that part of the coal field. One of those faults was proved at the New Moss Colliery to be over 400 yds. in vertical displacement, but at Denton, three miles to the east of the colliery, the displacement was found to be only of 30 yds. Another fault which was supposed to be 170 yds. displacement at Bredbury had only a few' feet displacement at Denton, less than two miles away. In the first-mentioned fault, the reduction in throw was towards the east, and in the other towards the west. He should like to ask Dr. Hickling what, in his opinion, had caused that variation, and whether he knew of any otiier similar occurrence. With respect to the Croxteth borings referred to in the paper, he was of opinion that the twm holes were placed in unsuitable positions, and that a third hole, midway between them, would have given much better data on the value of that part of the