THE COLLIERY GUARDIAN. 431 March 2, 1917. _________________________________________________________________________________________________________________ pared with the preceding year. The death-rate per 1,000 persons employed above ground was 0’648, and surface accidents account for 10’1 per cent, of the deaths in and about all mines. Three accidents each caused two deaths, and 128 caused one death each. There were 27 fatal accidents by machinery on the surface. As in previous years, many of these accidents would apparently have been prevented by the more secure fencing of the moving parts of engines, revolting shafts, gearing, etc., and were it made a practice not to oil or clean machinery whilst in motion. Sixty-three persons were killed on surface railways, sidings, or tramways. This is a decrease of nine in the number of deaths as compared with the preceding year. There were four fatal accidents on the surface due to electricity, and 37 miscellaneous fatal accidents, causing 39 deaths. Table D gives the number of deaths from accidents and the death rate per 1,000 persons employed, and per 1,000,000 tons of mineral raised in the various districts. Table C.—Fatal Accidents and Deaths at all Minhs under the Coal and Metalliferous Mines Regulation Acts, arranged according to place or cause. Coal Mines Act. ' Metalliferous Mines Act. Place or cause of the accident. , Separate accidents. Per cent, of total accidents Deaths from accidents. Per cent, of total No. of deaths. Av. for preced- ing 5 years. Separate accidents. Per cent, of total accidents. Deaths from accidents. Per cent, of total No. of deaths. Av. for pre- ceding 5 yrs. 1 1 Separate | accidents. Deaths. Separate accidents. Deaths. I. Underground accidents: 1. Explosions of firedamp or coal 16 1’3 44 3’2 16’6 229’8 dust 2. Falls of ground 656 54’3 673 51’9 590’2 607’2 7 36’8 8 38’1 14’4 16’4 3. Shaft accidents 48 4’0 61 4’7 73’8 I 84’6 2 10’5 2 9’5 7’0 7’0 4. Miscellaneous 362 29’9 392 30’2 366 4 ! 379’4 6 31’6 7 33’3 7’8 8’2 II. Surface accidents 127 10’5 130 10 0 154’4 | 156’6 4 21’1 4 19’1 5’4 5’4 Total 1,209 100’0 1,297 100’0 1,201’4 ' 1,457-6 19 100’0 21 100’3 34’6 37’0 Table D. Inspection division. Number of deaths. Death-rate from accidents per 1,000 persons employed. Number of deaths per 1,000,000 tons of mineral raised. 1915. 1915. 1914. Total. Under- ground. Above- | ground. Total. Under- ground. Above- ground. Total. 1915. 1914. 1. Scotland 130 19 149 1’35 0’73 1’22 1’09 3’75 3’64 2. Northern 203 24 227 1’41 0’59 1’23 0’80 4’36 3’41 3. York and North Midland 236 30 266 1’33 0/59 1’16 0'84 3’91 3’25 4. Lancashire, North Wales and Ireland 126 11' 137 1’53 0’47 1’30 1’12 5'46 5’28 5. South Wales 304 27 331 1’79 0’82 1’63 1’61 6’54 6’98 6. Midland and Southern... 168 19 187 1’99 0’76 1’71 1’04 6'47 4’31 Total for the U.K.... 1,167 i 130 1,297 1’55 0’65 1’36 1’08 4 90 4’37 During the year 1915 there were 143 prosecutions of owners, ag> nts and managers for offences under the Coal and Metalliferous Mines Regulation Acts, resulting in 107 convictions. In addition, one summons was taken under the Cruelty to Animals Act, and was dismissed There were also 964 prosecutions of work- men for offences under the Coal and Metalliferous Alines Regulation Acts, resulting in eight convictions for interfering with the ventilation, 31 for contravention of provisions about safety lamps, 345 for contravention of provisions about matches and smoking, 56 for contra- vention of rules about explosives, 37 for contravention of provisions about timbering, 46 for contravention of provisions about trams or tubs, 47 for contravention of provisions as to travelling on haulage roads or travel- ling or working on roads or working places not made secure, two for contravention of rules as to electricity, 12 for disobeying orders, seven for wilfully damaging or removing apparatus, etc., 47 for contravention of rules as to care and treatment or cruelty to animals, 45 for being about the mine in a state of intoxication, and 216 for miscellaneous offences. ______________________ EMPLOYMENT OF BOYS AT MINES. Statistics are given in Part II. of the General Report on Mines and Quarries in 1915, which show that the occupation of boys underground is slightly less dangerous than that of persons over 16; the average death-rate for 10 years per 1,000 persons employed underground being 1’40 in the case of the lads under 16, and 1’50 in the case of persons above that age. The following table gives the death-rates per 1,000 persons employed underground, under and above 16 years of age respectively, at all mines, for the years 1906-1915:— Age. ________ <--------K---------Total. Under 16. Above 16. 1906 ................. 1’26 ... 1’44 ... 1’42 1907 ................. 1’33 ... 1’46 ... 1’46 1908 ................. 1’52 ... 1’46 1’47 1909 ................. 1’59 ... 1’62 ... 1’62 1910 ................. 1’77 ... 1’93 ... 1’92 1911 .......................... 1’26 .. 1’31 ... 1’31 1912 _________________ 1’09 ... 1’28 ... 1’27 1913 ........................... 1’37 ... 1’76 ... 1’74 1914 ................. 134 .. 1T8 ... 1’19 1915 ................. 1’44 ... 1’55 ... 1’54 Averagesfor 10 years 1’40 ... 1’50 ... 1’49 BOILER FEED WATER. Mr. W. Diamond, of Marley Hill, in ’addressing the members of the Northern section of the Coke Oven Managers’ Association on this question at their meeting at Durham last Saturday, said that the subject might not seem suited to that association, but, as the result of many years’ experience of the class of water usually supplied to coke works for steam raising and chemical uses, he thought.the topic might be of interest. He knew of only one plant where the water supply was from the town main, the rest of the supplies being either from adjacent pits or from rivers or brooks. That water con- tained an abundant quantity of suspended matter, and also an abnormal quantity of dissolved salts, some of which were injurious, whilst others were normal. The effect of all these impurities upon the plant was, of course, detrimental. In the gas coolers, where the water for cooling purposes flowed counter to the direction of the gas, one found with such water that the deposit adhered to tlie tubes, together with the salts which had crystal- lised out in the hotter cooling chambers, very quickly and materially affected the efficiency of the cooling apparatus. That applied throughout, wherever water was required for cooling purposes, such as in concen- trated ammoniacal liquor, benzol plants, etc. The quantity of water used in condensing was so great that he> did not suggest that it should be treated further than that, before using, it should be allowed to settle for as long a time as possible in a •'reservoir,, to enable the suspended matter to subside. The water required should then be drawn from the top. Water for steam raising should be treated, unless, of course, it was suit- able without treating. He had known several plants where the word “ steam ” had been sufficient to cause trouble, especially where boilers belonging to- two departments were coupled; but that experience was gained some years ago, before coke ovens had attained their present high standard of efficiency. The general impurities in water which had the greatest detrimental effect in steam boilers were calcium bicarbonate, magnesium bicarbonate, magnesium sulphate, and calcium sulphate. It was a working principle to sludge boilers frequently during the day in order to clear them of deposits and to reduce the bulk of water which had become concen- trated. He had examined samples of water taken from boilers at work at different collieries, and had found them to give the following results :— Boi.li?g Na„SO,. NaCl. SPec.iia° point. 2 4 gravity. 1. 103 ... 3’85 ... 0’16 ... 1’041 2. 101’8 ... 0’63 ... 0’03 ... 1’088 3. — ... 2’88 ... 0’68 ... — 4. 102 ... 0’92 ... 0’08 ... 1’020 5. — ... 8’68 ... 2’73 ... — 6. — ...- 8’48 ... 3’15 ... — From these it could be deduced that the working of the boilers was not altogether most efficient. It was, he was sure, unnecessary for him to point out that, whenever a boiler tube or shell was permitted to be covered by scale, the efficiency became considerably less, and, if the neglect continued, the danger arose of explosion, or, at least, of the burning of the tubes. He had seen one tube red-hot. Possibly the scale would crack, and the water would get to the hot plate, and cause considerable damage. Speaking broadly, if the water contained 20 degs. hardness, it would, cause, approximately, 20 per cent, loss in fuel, either coal or gas. There were not many supplies where the water was less than 30 degs. of hardness. It thus became apparent that, in order to do the best for the boilers, they should, at least, make the water suitable for steam raising, by which he meant that the water should be chemically treated to reduce the hardness to about 4 to 6 degs., which was the best for that purpose. There were temporary and permanent hardnesses. The former might be said to be got rid of by heating, but the latter could not. Therefore, in order to devise a means of getting rid of both, an analysis of the water, which need not embrace more than to give information regarding free carbonic acid, alkalinity, lime, and magnesia, was necessary. The temporary hardness might be removed by the addition of lime, when calcium carbonate was formed as a precipitate. If magnesium bicarbonate was present, a double quantity of lime was required, in order to precipitate the magnesium as hydroxide. There were many formulae for obtaining analytical results upon which the softening of water depended, but he though that the simplest and best was the routine devised by Anderson :— (1) Free Carbon Dioxide. —If the water contained an appre- ciable quantity of CO2, arrangements must be made for treating it. Seyler’s method of estimation was to titrate with standard sodium carbonate, using phenolphthalein as indicator. (2) Alkalinity.—This was determined by titration with standard hydrochloric acid, using methyl orange as indicator. (3) Lime and Magnesia.—These might be estimated by many methods, but the one found to be most 'advantageous was that devised by Pfeifer and Lunge. Its purpose was to precipitate the calcium and magnesium as carbonate and hydroxide respectively. A- quantity of water, 100 c.c., was acidified with hydrochloric 'acid very slightly. The whole was evaporated down to 30 c.c., or thereabouts, and was then cooled, made up to 100 c.c., and exactly neutralised, using methyl orange as indicator. To that was added 10 c.c. of decinormal sodium carbonate and decinormal caustic soda, and the mixture was boiled for two or three minutes. After cooling, it was again made up to 100 c.c., and filtered through a dry filter. The excess alkali was determined by titration with decinormal hydrochloric acid. The difference between the added quantities and those found in the last titration showed the quantity used in the precipitation. If that difference was multiplied by 3-5, it gave the total degrees of hardness. It had been found by Pfeifer and Anderson that, if caustic soda were added to very dilute solution of magnesium salts, even in the presence of calcium salts, magnesium hydroxide was precipitated. Upon that was devised the following method of estimation : 100 c.c. of the water was slightly acidulated, and evaporated to 30 c.c. It was cooled and exactly neutralised. To it was added 10 c.c. of standard caustic soda solution, and the whole was then made up to 100 c.c. After some hours, 50 c.c. of the super- natant liquid was withdrawn and titrated with decinormal hydrochloric acid. A similar calculation as in the estima- tion of lime and magnesia was made, which gave the degrees of magnesia, hardness. Thus they obtained all the knowledge necessary for the softening of water. The only thing required was to know how to use it. The mere adding so much lime and so much soda ash would not, unless the engineering of the process’had been properly considered and devised, yield the expected results; they might, in fact, cause trouble in the boiler mountings, and possibly spoil some other process where open steam had been used. Three vital points should be observed :— (1) Temperature of the water to be treated. If clean waste steam could be utilised, it was profitable to do so, both for efficiency in softening and economy in fuel. (2) Rate of flow of water during treatment. (3) Sufficient area of filtering material to clarify the water of any precipitate. It was assumed that, when the chemicals were added to the water, they would be thoroughly mixed. This could be done either mechanically or by the flow of the water to be treated. There were plants which had both devices. After having added the chemicals and taken the precautions he emphasised, it was necessary to find if the laboratory results had technically proved correct. It had been found that 60 per cent, of the waters throughout the country contained a fairly large quantity of neutral salts, chiefly sodium sulphate. There was no doubt that to remove neutral salts from the water would be costly, and would not yield any benefit. Therefore, it was necessary to find if the laboratory research had obtained the desired results. Two simple tests — the hardness by the soap test, and the alkalinity by phenol- phthalein and methyl orange—would prove the results. After obtaining the hardness by the soap test, they pro- ceeded to find (1) the phenolphthalein alkalinity, and (2) the total (methyl orange) alkalinity. 100 c.c. of water was titrated with decinormal hydrochloric acid, phenolphthalein was added, and the degree of alkalinity was noted. One or two drops of methyl orange were added, and the titration was continued, the final value giving the total alkalinity. The phenolphthalein value was multiplied by two, and the methyl value was sub- tracted from it. If there was a positive remainder, caustic alkalinity was present; if there was no remainder, the alkalinity was carbonate; if the result was negative, there was bicarbonate present. As observed by Anderson, if the quantity of soda had been proper, the hardness and total alkalinity would be the same. If the soda was in excess, the total ‘alkalinity exceeded the hardness, and, if deficient, otherwise; by methyl orange, if the lime added had been sufficient, the phenol- phthalein value would be little -more than the total alkalinity as shown by the formerA methyl orange titra- tion, which meant that a little-caustic was present. If insufficient- lime had been added, then the value would be less than half, and vice versa. If one knew the water which one had to treat, slight variations might be allowed to ensure the better result of the treatment. It was not always a proper way out of the trouble to resort to the town supply of' water, for that might be equally as bad as the water discarded. The hardness of town water supplies differed, as follows: Durham, 17 degs.: Gates- head, 11; Inverness, 2; Darlington, 6; Gainsborough, 23; Ipswich, 20; Aberdeen, 1-5; Banbury, 25; and Lanark, 1’5. It was desirable, therefore, to look into the nature and quality of the substitute before deciding on it.