LiDrtniii OF THE UMVtrfSITY OF ILUNOiS 28 DEC1914 THE COLLIERY GUARDIAN AND JOURNAL OF THE COAL AND IRON TRADES. Vol. CVIII. FRIDAY, DECEMBER 4, 1914. No. 2814. Midland Institute of Mining, Civil and Mechanical Engineers. There was a well-attended meeting of the Midland Institute of Mining, Civil and Mechanical Engineers on Friday, November 27, at the Applied Science Depart- ment of Sheffield University. Mr. Walter Hargreaves (president) was in the chair. Three new members were elected. A New Firedamp Indicator. Mr. H. R. Webster (Horsforth) read a paper on “ A Firedamp Indicator ” (see p. 1182). The reading of the paper was followed by a demonstration, showing the readings in mixtures of 1, 2, and 3 per cent, of gas. Prof. O’Shea (Sheffield University) said the president had asked him to bring to the notice of the members some results Mr. Webster and himself obtained from tests of the apparatus with a gas which consisted largely of methane, viz., 70-6 per cent, methane, 11-6 per cent, hydrogen, and 17'7 per cent, air; the specific gravity of the gas was 0-579; 1 per cent, of this mixture was introduced into a Clowes chamber, and two instruments, A and B, were tested. A indicated 0-5 and B 0-4 per cent. The instruments remained in the chamber until the index finger fell to zero, and then instrument A was brought out into the air, when it immediately showed a reading of —0-4. In a second experiment both instruments were taken out of the chamber, and remained in the air until the finger reached zero; 2 per cent, of gas was introduced into the chamber, and then the instruments put in. A showed 1*15 per cent, of gas, and B 1 per cent. The instruments remained in the chamber, and 1 per cent, more gas was added, making a total amount of 3 per cent. The increase in the read- ings after the addition was as follows : A 0-4 per cent., B 0-2 per cent. They were then tried in 1 per cent, of coal gas; instrument A showed 1| per cent, and B 1 per cent. The apparatus remained in the chamber until zero was reached, and then brought into the air; A showed —1| per cent, and B -1 per cent. The fourth experi- ment was in 2 per cent, of coal gas, when instru- ment A showed 21 per cent. These rates were double those obtained with the marsh gas, which might be accounted for by a difference in the specific gravity of the gases. Calculation of the specific gravity of the coal gas used made from an analysis made some time ago was little more than half that of the mixture—only 0-357—so that the results obtained by marsh gas were naturally only about half of those which would be got with the coal gas. Further experiments were made with mixtures of methane and carbon dioxide, having a specific gravity of about 1, and on adding in the Clowes chamber sufficient of this mixture to give 1 per cent, of methane to the atmosphere, in three experiments the following results were obtained :— Instrument “ A.” Instrument “ B.” (1) 0’1 per cent. ... 0'0 per cent. (2) 0-26 „ ... 0'15 „ (3) 0-27 „ ... 0'25 „ The differences in experiments 2 and 3 were probably due to the fact that the apparatus had not been cleared of the carbon dioxide, although in each case the instru- ments were allowed to come to zero in air before being introduced in the chamber. A sixth experiment was made with a quantity of the mixture equivalent to 2 per cent, of methane, and instrument A showed 0-525 and B 0-4. The instruments were then brought back to zero in the chamber, and taken out into the air, when imme- diately A gave a reading of —0-75, and. B —0-6 per cent. The instruments were finally tested in an atmo- sphere containing 1 per cent, methane mixture and 1 per cent, carbon dioxide, when A indicated 0-26 of marsh gas, and B 0-2. It was evident from these experiments, concluded Prof. O’Shea, that an instrument of that.kind must be calibrated with gas of the same density as marsh gas. If this were not done, the readings obtained could hardly correspond with the percentage of gas which was in the atmosphere. The density of the atmosphere which -was tested had always been the diffi- culty with instruments based on diffusion, and he would like to ask Mr. Webster what experiments he had made with mixtures of gases beyond those they had carried out together, because it seemed to him to be a matter of considerable importance in the determination of the quantity of firedamp present. They might have fire- damp, carbon dioxide, mixture present in such propor- tions that the instrument would show very little fire- damp at all. There were other defects to which instruments based on diffusion were subject. Many of them were defects which probably Mr. Webster had overcome, but the defect due to the fact that the atmo- sphere to be tested did not contain pure marsh gas prevented the instrument from correctly registering the .W ' : . i ■ ' "A: ■ ' ® i Photo] [IF. Gothard, Leeds. Lieut.-Col. Joseph Hewitt, of Ouslethwaite Hall, Barnsley, who has been appointed to command the “ Barnsley Battalion ” of Kitchener’s Army, is prominently associated with the local coal- mining industry. He is the managing director of the firm of Messrs. Fountain & Burnley Ltd., owners of the North Gawber and Woolley Collieries, and also of the firm of Messrs. George Fountain & Sons Ltd., owners of the Haigh Colliery. He is President of the Barnsley and District Colliery Owners’ Associa- tion, and is the director of many local kindred concerns, including that of the great firm the Rylands Glass & Engineering Co. Ltd. It may be added that Lieut.-Col. Hewitt’s son is also serving his country. percentage of methane present unless the gases which were not methane were removed. Mr. Webster said that Prof. O’Shea had tested the instruments at his (Mr. Webster’s) special request, to see what the result would be, because he had been informed by an authority, that an equal amount of carbon dioxide would neutralise an equal amount of air, and by the experiments kindly undertaken by Prof. O’Shea he did not think that that was so. There was no difficulty in fixing the instrument with the absorbent, as shown on the drawing, but the more complications that were introduced into an instrument, the worse it was for the deputy to handle. Absorbents were nasty things, unless they were applied in such a way as shown, taking the form of a brass tube filled with soda of lime, through which the gas was pumped, the reading taken, and the instrument sealed, and at the next place at which it was tested it would not go back to zero, and if the hand receded on the minus side it was pure gas, because the carbon dioxide was being absorbed. If Prof. O’Shea would permit him, he would bring an instrument with which, with mixtures of carbon dioxide and methane, they could settle the question once and for all. He maintained that he could take the whole of it out, and give an absolutely pure reading of methane. The reading he gave that day was the explosibility of the gas; if carbon dioxide neutralised it.at all, it gave the percentage of gas over and above the carbon dioxide. The gas he used was not of the same density as Shef- field gas; this gas was exactly double the value of methane, and the instrument read 0-5 for 1 per cent, of methane. He had been to several collieries, and had chemical analyses taken against his readings, and they appeared to be very much out, but when he applied Prof. O'Shea’s solution to it they were absolutely correct to within a second decimal point. Prof. O’Shea said that only bore out his contention that Mr. Webster must graduate his instru- ment to the gases he -was going to test. Not all mine gases were alike, and that was where the difficulty came in. The President suggested ■ that Mr. Webster should be given the further opportunity of carry- ing out the experiment to which he had referred, and the further discussion of his paper adjourned till then. He moved a hearty vote of thanks to Mr. Webster. Mr. Mottram, in seconding, hoped that Mr. Webster would elaborate his paper, in reference especially to his experiments made underground. The vote of thanks was heartily accorded. The Case for the Electric Lamp. Mr. William Maurice then read a paper on “ The Case for the Miner’s Electric Lamp ” (see p. 1181). The President, in opening the discussion, sug- gested that this should relate to both Mr. Maurice’s paper and that by Mr. E. A. Hailwood on “ Miners’ Electric Lamps Compared with the Combustion Tube Oil Lamp” (read at the previous meeting of the institute—see Colliery Guardian, October 2, 1914). Personally, he had been greatly struck by many of the state- ments in Mr. Hailwood’s paper, -which made him wonder whether, in adopting electric lamps at the collieries with which he was connected, he had been 11 a day before the fair.” He desired simply to put before them the results he had been at some pains to record in connection with his collieries. They had there 4,500 electric lamps, and they had been in use for nearly 18 months — sufficiently long to give a complete 12 months’ record. The figures he had put together represented the whole cost — stores, ,replacements, and everything else. Everything in connection with the lamps had suffered replace- ment except the outer cases. The vulnerable parts of the lamp—bulb, battery, and all the parts that had to be renewed and kept up-to-date—and the depreciation of the cases of lamps were all included in his figures, in that they took a percentage of spares and included them so as to keep right on the question of depreciation. They had had in actual work 4,275 of the “ Ceag ” pattern lamp. The total number of shifts worked in the time under review was 983,250, and the total cost per lamp per shift had been 0-3141d. Midti- plying that by five—the average number of shifts per week—brought out the total cost to l-5705d. per week per lamp; that was the cost of the “ Ceag ” installation at their collieries. He had no doubt whatever that the lamps would be maintained at that cost, depreciation included, and all wear and tear stood. He agreed with Mr. Maurice that to obtain such results as he had quoted they required very considerable attention, and that they professed to give. He was referring to the cost of the