March 31, 1898] 



NA TURE 



523 



The total value of all the minerals worked in the kingdom 

 was 69,088,366/., from which it will be seen that the value of 

 the coal alone was practically five-sixths of the whole amount. 



The number of separate accidents in mines was 886, involving 

 the loss of 1065 lives, of which 147 were the victims of four 

 explosions of fire-damp or coal-dust. The number of separate 

 accidents in quarries was 117, in which 124 lives were lost. 



A comparative table showing the death-rates from mining and 

 quarrying accidents in different countries per icxx) persons 

 employed, brings out some remarkable facts. Taking the 

 column which represents the total for underground and surface 

 for the year 1896, or in the absence of the figures for 1896 

 those of 1895, we find the following rates for the coal mines in 

 some of the principal coal-producing countries of the world : — 



. Belgium 

 France (1895) 

 German Empire ... 

 Russia {1894) 

 United Kingdom ... 



United States (1895): 



Colorado 



Illinois 



Indiana 



Indian Territory 



Kentucky 



Missouri 



New Mexico ... 



Ohio 



Pennsylvania : — 



Anthracite 



Bituminous 



Utah 



ri4 

 I-I9 



2-57 

 1*29 

 I 48 



375 

 I 94 

 270 

 I 64 

 I 02 

 2-07 

 16-88 



2"II 



2-924 

 1-825 

 1-50 



According to M. Louis Lacombe, who compared the death- 

 rates from accidents in mines in quinquennial periods, the last 

 of which was 1890 to 1895, the ratios are as follows : — 



Russia 2-90, Belgium 2-38, England 2-18, France 1-37. 



The death-rate frcjm accidents to railway servants in the 

 United Kingdom for the year 1896 is given as i-oi per 1000. 

 The category includes such classes as carmen 0-47, clerks o*x7, 

 mechanics 0-33, and signalmen 0-55, whose occupations are not 

 by any means dangerous. On the other hand, the death-rate 

 amongst those who have to do with coupling and uncoupling 

 and making up the trains is infinitely more serious, such as 

 shunters 4-94, yardsmen, 3-27, guards and brakesmen of goods 

 trains 3-03. The highest of these figures pales before tho.se 

 applicable to sailing ships, amongst which we find : — 



British sailing ships (1896) 

 German „ „ (1893) 



12-9 

 15-8 



These figures prove conclusively that the miner's calling, when 

 brought into comparison with some other kinds of employment, 

 is not of such a dangerous nature as is generally supposed. As 

 having a bearing upon this question, however, it may be stated 

 that one of the most gratifying features of the report is the curve 

 given on Plate 4, which shows the death-rate per 1000 persons 

 employed underground in coal-mines to have been reduced 

 from the appalling figure of 5-5 in 185 1 to 1-62 in 1896. This 

 result — upon the attainment of which the Home Office, the 

 Inspectors of Mines, and the mining community generally may 

 well be congratulated — is undoubtedly due to the efforts that 

 have been made by means ot legislation and inspection to 

 remove the causes which formerly led to such a lamentable loss 

 of life. The loss of 147 lives in four great explosions in the 

 year 1896 is a black spot in the record which ought never to 

 have been there. I am glad to observe that the year 1897 has 

 been entirely free from anything of the same kind, and I feel 

 confident that if the new regulations regarding the watering of 

 dusty places, and the use of explosives are attended to, or en- 

 forced with unflinching severity, we shall have seen the very 

 last of such affronts to humanity and common sense. 



The fines imposed upon owners and managers of mines for 

 contraventions of the Mines Acts amounted to the insignificant 

 sum of 258/. 135. 9</., while the workmen for similar offences 

 paid 459/. ds. &/. 



The outputs of coal from a few of the principal coal-pro- 

 ducing countries were as follows : — 



NO. 1483, VOL. 57] 



From these figures, with which I propose to bring this short 

 and necessarily fragmentary notice to a close, it will be seen 

 that this country still heads the list ; but the United States 

 are quickly overtaking us, and will, no doubt, come into the 

 first position in the course of the next few years. 



W. Galloway. 



CALCIUM CARBIDE AND ACETYLENE. 



A T the meeting of Institution of Civil Engineers on March 

 ■^ 15, a paper on " Calcium Carbide and Acetylene" was 

 read by Mr. Henry Fowler, and is here abstracted. 



Acetylene was first isolated by E. Davy in 1837 from potassium 

 carbide, a by-product of Sir II. Davy's method of manufacturing 

 potassium. In the middle of the century Berthelot investigated 

 its properties, and Wohler produced it from calcium carbide. 

 During the past few years it has assumed commercial importance 

 owing to the development of the electric furnace, in which 

 calcium carbide can be readily produced from lime and carbon. 

 The furnaces used consist essentially of crucibles with carbon 

 rods forming the positive electrode and a bottom plate lined 

 with carbon for the negative. In the more recent furnaces these 

 crucibles are mounted on small trollies so that they may be run 

 out of the furnace when ready and a fresh one inserted without 

 loss of time. The carbide formed is a hard, dense substance of 

 reddish colour, unacted upon by most of the ordinary reagents. 

 It is, however, rapidly decomposed by water into acetylene and 

 lime, giving 5-9 cubic feet of acetylene, at a temperature of 60° 

 P\ and a pressure of 30 inches of mercury, per I lb. of carbide. 

 As the power required theoretically to produce i lb. of calcium 

 carbide in an electric furnace is more than 2 H.P. hours, its 

 manufacture is at present restricted to localities where power is 

 cheap, as for instance where water-power is available. 



Acetylene is a colourless gas with an intensely penetrating 

 odour, and is slightly soluble in water, and extremely so in some 

 other fluids. It is endothermic, giving 407 calories per cubic 

 foot, whereas theoretically its value is 336-5 calories. As an 

 illuminant it gives the most brilliant light of all gases, 5 cubic 

 feet per hour under suitable conditions giving 240 candle-power. 

 For small consumptions, however, this value is not obtained, 

 and ordinary burners after a short time became clogged with 

 soot. The latter defect can be overcome by the use of an injector 

 burner, which, however, requires a higher pressure. Various 

 diluents have been suggested, but have not been tried on a 

 practical scale. The flame has a high actinic value, and causes 

 light colours to appear lighter, and dark colours darker than when 

 exposed to sunlight. The gas, when inhaled, combines with the 

 haemoglobin and renders the blood incapable of taking up oxygen, 

 and thus causing suffocation. It has, however, been shown that 

 it is no more dangerous in this respect than coal gas. 



Acetylene unites with copper, in the presence of moisture and 

 ammonia, forming copper acetylide, and this when in a dry state 

 is violently explosive. Silver is similarly acted upon. 



Owing to the difficulty of obtaining the materials used in pro- 

 ducing calcium carbide in a pure state, phosphoretted and sul- 

 phuretted hydrogen and ammonia are often found in the gas, 

 and these should be removed by passing the gas through water 

 and an acidified solution of a metallic salt. Nearly all propor- 

 tions of air and acetylene are explosive, the gas itself being 

 decomposed at 780° C. At higher pressures than 2 atmospheres, 

 if this temperature is attained by a part of the gas, it is com- 

 municated throughout the whole mass and a violent explosion 

 occurs, which causes the pressure to rise to eleven times the 

 initial pressure ; but owing to cooling by radiation, &c., this is 

 not reached in practice. Acetylene can be readily liquefied, 

 having a critical temperature of 37° C. and pressure of 68 



