PETROLEUM 409 



and oxygen under pressure can be obtained in portable cylinders, and repairs executed in the 

 confined space of a ship's hold or even in the boilers themselves. 



The trade in cylinders of dissolved acetylene has, as might be expected, expanded rapidly 

 both in Great Britain and elsewhere, this being due partly to the advance in oxy-acetylene 



welding, but more largely to the enormous increase in the number of motor- 

 Dlssolvcd vehicles, the headlights from which are most conveniently supplied with acet- 

 ace y ene. ylene from a cylinder of dissolved gas, which does away with the trouble 

 incidental to a portable generator. 



Another direction in which the use of acetylene has made enormous strides in America 

 is for self-starters for motor-cars, of which some fifteen different kinds are in use in the 



United States. In one class of self-starters the pressure existing in the acet- 

 Self-starters. ylene cylinder is used to force a charge of gas and air. into the explosion cylinders 



of the motor engine, where it is fired by the spark and starts the engine, the 

 "Disco" automatic self-starter being one of the best of this class; while the "Prest-O- 

 Starter" may be taken as the type of a second class, in which low pressures only are used, 

 the mixture of gas and air being pumped into the cylinders in proper firing order. 



In 1896 it was shown that when acetylene is passed through a red hot tube it undergoes 

 instantaneous decomposition with deposition of carbon and liberation of hydrogen, the 



carbon being rendered incandescent b> the exothermic decomposition, and that 

 Polymerlsa- t ^ e temperature at which this takes place could be raised by dilution with 

 acet Iene hydrogen; when this was done the acetylene underwent condensation into 



benzene and other hydrocarbons. R. Meyer has now repeated these observa- 

 tions. on a larger scale. The apparatus consisted essentially of two vertical tubes, electrically 

 heated, and a mixture of acetylene and hydrogen was passed slowly through them, the tem- 

 perature being so arranged that separation of carbon was to a large extent avoided. The first 

 tube was heated to 650 C., and the second to 800 C., when it was found that a quantity of a 

 light brown tarry liquid was formed, and that the gases leaving the apparatus contained 

 methane. In some cases the yield of liquid was about 60 per cent of the weight of acetylene 

 used, and contained nearly 20 per cent of its weight of benzene. Other hydrocarbons 

 identified were toluene, napthalene, anthracene, indene, diphenyl, fiuorene, pyrene and 

 chrysene; and further experiments with acetylene and hydrocyanic acid confirmed Sir 

 W. Ramsay's observations that these bodies condensed to form pyridine bases. 



A considerable amount of work has been done in utilising calcium carbide for the fixation 

 of atmospheric nitrogen. In order to do this crushed calcium carbide is heated to a tempera- 



ture of 800-1000 C. in an electric furnace, and nitrogen, generally obtained 

 ' ^Y liquifying air by the Linde process and allowing the nitrogen to distil off, 



is then passed through the red hot mass and converts the calcium carbide into 

 calcium cyanamide, CaCN2. This is now recognised as an extremely valuable manurial 

 matter, as it slowly evolves ammonia under the influence of moisture, according to the equa- 

 tion: CaCN 2 +3 H 2 O = CaCO 3 +2 NH 3 . There is a large installation at Odda, in which 

 196 electric furnaces are employed, and about 30 tons of calcium cyanamide, containing 

 1 8 per cent of nitrogen, made per 24 hours, whilst the world's production for the past year 

 amounts to nearly 200,000 tons. (ViviAN B. LEWES.) 



THE PETROLEUM INDUSTRY 1 



The winning of petroleum in regions of proved productivity, and, concurrently, the 

 discovery of new sources of supply, are being greatly stimulated by the rapidly increas- 

 ing employment of oil fuel for power purposes, both as a substitute for solid fuel in steam- 

 raising, and through the medium of the internal-combustion engine. 



Since its inception half a century ago the petroleum industry has advanced to a posi- 

 tion of great importance, mainly in supplying a cheap, convenient and efficient light, 

 and an excellent lubricant for machinery. During the past few years it has also furnished 

 the motor-spirit which drives our automobiles, motor boats, submarines, hydroplanes 

 and aeroplanes. Now, however, it is entering upon a new era, in becoming a great fuel 

 industry, and its further expansion promises to be far more rapid, for it is evident that if 

 there is to be any large substitution of oil for coal as a source of power the output of oil 

 will have to be greatly increased. At present the world's production of petroleum does 

 not amount to much more than 5 per cent of the output of coal, even allowing for the 

 higher calorific value of the liquid combustible. The general employment of motor- 

 spirit has, of itself, contributed largely to the present profitable character of the 

 business, though the high price at which this product is now sold is leading to the use 

 of distillates of higher specific gravity and lower volatility, of which a far larger percent- 



1 See E. B. xxi, 316 et seq. 



