900 ____________________________________________________________________________________________________________ THE COLLIERY GUARDIAN. May 12, 1916. CURRENT SCIENCE AND TECHNOLOGY. Dust Sample Tubes. Mr. F. W. Watson (Journal of the Chemical, Metal- lurgical, and Mining Society of South Africa) states that, in view of the difficulty of obtaining glass tubes for sampling dust underground, and rubber corks for Lauf tubes, a sampling tube made of metal has been found to give satisfaction. The tube which contains the sugar is 2 in. in internal diameter, and about in. in depth, and holds about 50 grammes of sugar. It is fitted with fiat screw caps at either end, and another screw cap with a small pipe, l|in. long and Jin. internal diameter, can be inter- mW 24 SAMPLER Z’O/? T£3T/NG> ________ I 3 BARREL closed FOR TRANSPORT hydrocarbons, facilitates ignition and minimises carboni- sation inside the engine; (2) a low “ free carbon ” con- tent, as the greatest difficulty is experienced in obtaining complete combustion, and a clear exhaust when fuels rich in this substance are in use; (3) a high calorific power, as .upon this value is dependent the amount of work obtainable from unit weight of fuel; (4) a moderately low viscosity to allow the oil to flow through the engine service pipes in cold weather, and giving a more effective pulverisation, thus increasing the thermal efficiency; (5) very little water, less than 2 per cent., as when present in larger quantities the drops of water cause irregular running and misfiring; (6) low coking value, never over 15 per cent., as this value is a direct measure of the liability to form deposits in the engine; and (7) low ash content, not exceeding 0-15 per cent. A New Rock Drill Bit. The Canadian Mining Journal states that the Calumet and Hecla and subsidiary companies operating in the Michigan copper district, by the use of a new type of drill bit, have increased efficiency by 40 per cent. The Carr bit was first called to the attention of the Calumet and Hecla Alining Company by the Ingersoll- Rand Company, who had used it with considerable success at a mine in the south. As originally designed, it did not prove to be very efficient in the Michigan copper mines, and it was only by changing the various angles of the bit, reducing the size of drill steel used, and insisting upon very accurately made bits, that satis- factory results were finally obtained. The theory of the bit is that if the two edges of the wings of the bit are kept out to the full gauge diameter of the cutting edge, then these edges act as reamers— the cutting edges doing the rough chipping—and the diameter of the hole is maintained. This makes it possible to start a hole with a very small diameter, and drill it to a considerable depth at a great relative speed. The reaming quality of the wings of the Carr bit make it possible to change the gauge of the drills only yL in for each 22 in. run of steel on the amygdaloid lode breakage and the resulting loss of drill steel has conse- quently been greatly reduced. The anvil block chuck, and the resulting plain shank on the drill tsteel made it possible to use smaller and lighter steel, and therefore still smaller holes than were practicable with the ljin. round steel formerly in use. One-inch hexagon steel has therefore become the standard at the Calumet and Hecla and subsidiaries, except on the Osceola lode and at the Superior mine, where conditions were found to justify the use of J in. hexagon steel. The drilling speed of the Carr bit on the smaller steels now used is just about double that of the old crossb it on the IJin. round steel formerly used. By “ drilling speed ” is meant the depth of hole drilled per minute of actual reciprocating time. Since much of the work of the miner—such as rigging up, barring loose, changing drills, etc.—is not at all affected by the bit, his efficiency is not increased in proportion to the increase in drilling speed of the bit. However, there has been an actual increase in every mine, after a few weeks use of the bit, of about 40 per cent, in actual efficiency, and this without any extra effort-on the part of the miner. During the past four years many improve- ments have been made in drilling methods among the Michigan copper mines, and it is rather interesting to note that the increase of 40 per cent, due to the Carr bit is just about equal to the total efficiency of the miner of four years ago. ______________________________ EXPLOSIVES IN COAL MINES. NEW ORDER. The Homo Secretary has issued, under date April 14, 1916, an Order including the following explosives in the First Schedule of the Permitted List. changed. tLTiis last cap (the adapter) connects the tube to the suction pump. One adapter is sufficient for a whole series of tubes. A diaphragm of gauze, 260 aper- tures to the linear inch, is fixed in the tube Jin. from one end, and on this the sugar rests. When taking a sample, the fiat caps are removed and the tube screwed into the adapter, which is connected to the pump. After taking the sample, the tube is detached from the adapter, and the fiat caps replaced. When taken to the laboratory the outside of the tube is washed before the caps are removed, and the tube placed bodily in a beaker of warm water, care being taken that the water does not reach the top of the metal tube. The sugar is dissolved, and the dust passed through the fine gauze in the one operation, thus obviating the necessity for having a separate funnel with a gauze screen. When solution is complete, the tube is lifted out and washed, and the solution in the beaker is then ready for filtering. The tubes can be packed in a small compass, and the filtering area is large enough to allow a large sample to be. taken, without causing a partial vacuum between the tube and the pump. Fuel Oils from Goal. A short report has already appeared in the Colliery Guardian of the paper on the above subject which was read before the Manchester Association of Engineers recently by Mr. Harold Moore, M.Sc. The following table was given by the author, showing the properties of various tars :— Dynobel No. 3 lias the following composition :— Parts by weight. t Ingredients. Not more Not less than than N itro-gly cerine 16 14 Nitro-cotton Tri-nitro-toluol, I 0’75 .. 0*25 Di-nitro-toluol, and > together... Di-nitro-benzol ) 2*5 0*5 Nitrate of ammonium 54 51 Wood-meal (dried at lf,0degs. C.) 6 4 Chloride of sodium 26 24 Carbonate of magnesium 1 — Moisture 2 Dynobel No. 4 has the composition :— Parts by weight. Ingredients. Notmoie Not less than than N itro-gly cerine 16 14 Nitro-cotton Tri-nitro-toluol, i 0*75 .. 0*25 Di-nitro-toluol, and >■ together ... Di-nitro-benzol J 4 2 Nitrate of ammonium 47 44 Wood-meal (dried at 100 degs. C.) 6 4 Chloride of sodium 31 28 Carbonate of magnesium 1 — Moisture 2 — mines, and in the case of the Osceola lode the change in gauge is only in. every second run, or 44 in. On the Calumet conglomerate lode, which is very hard, the gauge is changed in. every 12 in., 1 ft. being the stan- dard run on this lode. Holes are also being drilled to a greater depth than was practicable with the bits formerly in use. Present practice is to use 12 and 14 ft. drills in stopes on most of the amygdaloid lodes and 14 and 16 ft. drills on the Osceola lode. The 10 ft. drill is the longest in use on the Calumet conglomerate lode, because of the “ fitchery ” character of the ground. It has been found that these longer holes are much more economical in the use of powder, saving about 20 per cent. The explosives shall be used only when contained in a case of paper thoroughly waterproofed with a mixture of ceresine and resin; with a detonator or electric detonator of not loss strength than that known as No. 6; the greatest weight of the explosives which may be used in any one shot holo shall not exceed 18 oz. in the case of Dynobel No. 3, and 30 oz. in the case of Dynobel No. 4; the explosives must have boon' made at the works of Nobel’s Explosives Company Limited, at Ardeer, Ayr- shire. Four ounces of Dynobel No. 3 gave a swing of 2’50 in., and four ounces of Dynobel No. 4 a swing of 2’35 in. to the ballistic pendulum, compared with a swing of 3’27 in. given by four ounces of gelignite containing 60 per cent, of nitro-glycerine. ____________________________ Exports and Imports of Mining Machinery.—The value of imports and exports of mining machinery during April are given below April. Jan.-April. 1915. 19 6. 1915. 1916. Analyses of Fuel Oils. Description. Sp. gr. at 15 degs. C. Water. . Ultimate composition. Ash. Coke. Net calorific value. Free carbon. C. H. O.&N. S. 'alories. B.Th U. Horizontal retort tar . 1*180 1*7.7 : 91*5 5*2 2*6 0*5 0 20 21*0 i 8,645 15,561 18*2 ■ Inclined retort tar 1’157 1*11 8-9 6’0 36 0*5 0*02 18*5 1 8,671 15,626 14*0 Vertical retort tar 1*089 2*25 88*0 6 8 38 0*6 0 03 6*1 ! 8,664 15,613 1*7 Otto Hilgenstock coke oven tar 1*208 6*00 ! 90*0 5-4 3-8 0*8 0-02 26*8 ; 8,624 15,523 23*9 Simon-Carves coke oven tar .. 1*090 0*50 1 88*1 5*6 6*1 i 0*2 0*07 6 0 ; 9,261 16,670 traces Chamber oven tar . 1*082 1*29 ! 88*2 6-9 4’6 0*3 traces 7*3 8,737 15,727 3 0 Low temp, carboni-ation tar... 1*058 3*00 | 85 8 8*1 549 0‘09 0*11 ’ 8*2 8,776 15,797 2*2 i W ater gas tar 1*051 0*59 J 92*2 6*8 0'4 0*6 traces 18*7 : 8,647 15,563 6*8 r Blast furnace tar 1*172 3*00 ! 89*5 5*75 0*55 0*84 0*36 I 23*4 ; 8,288 14,918 9*5 Blast furnace tar oil 0*974 none ; 87'25 9*8 2*59 0*36 none 1*05 9,213 16,637 none Oil distilled from low temp, tar . 0’884 none ■ 85 6 11*4 2’48 0*4 none 0*84 9,558 17,201 none Horizontal retort tar oil 1**65 1*00 90*1 6*8 2*4 0*50 0*2 1 3*0 9,243 16,637 none Pennsylvanian petroleum fuel oil ' 0-889 none 86*7 12*55 0*11 0 64 traces ’ 060 | 10,108 18,194 s none Imports ........... 9,037 ... 2,729 ... 28,260 ... 31,400 Exports ........ 47,304 ... 37,118 ...178,204 ...200,794 These figures are not inclusive of prime movers or electrical machinery. According to destination, the value of exports was as under :— April. Jan.-April. 1915. 1916. 1915. 1916. To— £ £ £ £ Countries in Europe 6,022 . .. 3,237 ...23,019 ... 15,771 United States of America.. 50 . 42 66 481 Countries in S. America .. 907 . .. 2,942 ... 3,681 ... 7,473 British South Africa . 18,343 . ..14,666 ...73,757 . 93,885 ,, East Indies 5,698 . .. 8,250 ...17,762 ... 25,842 Australia 565 . .. 1,408 ... 8,801 . ... 9,781 New Zealand 684 . .. 2,286 .. 2,460 . ... 6,665 Other countries 15,035.. .. 4,287 ...48,658 . ... 40,896 Total 47,304 . ..37,118 . .178,204 . ...200,794 , The following shows the value of exports of prime movers other than electrical :— April. Jan.-April. p-------A------- ------------A 1915. 1916. 1915. 1916. All prime movers (except £ £ £ £ Largely as the result of experimental work carried out by the author in the. laboratory of Mirrlces, Bickerton and Bay Limited, Hazel Grove, ho lias come to the following conclusions regarding the properties required in tars to allow their use in Diesel engines :—(1) A high hydrogen content, indicating the presence of aliphatic Carr bits drilling a “ rounder ” hole, it is easier to extract drills from the holes, and therefore it was soon found advisable to use anvil block chucks with plain shanks on the steels, thus doing away with the necessity of putting lugs on the drills as had been the practice since the introduction of the Leyner machine. Drill electrical) .......... 529,899...234,717...2,271,906...1,333,023 Rail locomotives .......146,830... 89,914... 905,843... 420,401 Pumping............................... 78,505 20,379... 195,176... 139,747 Winding.............. 40... 556... 2,537.. 3,121