ful alternating current arc is formed between two water cooled electrodes with high 

 voltage. This arc is spread out into a flat disk of flame by a magnetic field at right 

 angles, and the arc itself is formed in a flat furnace chamber. Air is blown through the 

 chamber, and the issuing gases are allowed to take up oxygen in a reaction chamber and 

 then conducted up towers filled with lumps of quartz down which water trickles. The 

 nitrous fumes produce nitric acid, which is concentrated and neutralised with either 

 soda or lime water, this producing sodic or calcic nitrate. This artificial nitrate has now 

 obtained a sale as a fertiliser. At Notodden in Norway the process is conducted on a 

 large scale, water power amounting to 30,000 H.P. or upwards being used for generating 

 the electric currents. Each arc furnace takes 700 kilowatts through which 25,000 litres 

 of air pass per minute, the whole plant being capable of 1,500 kilograms of 100 per cent 

 nitric acid per day. This factory has been open since 1905. In the apparatus of 

 Schonherr used by the Badische Anilinfabrik an arc is formed in a tubular furnace 

 between metallic electrodes, and air is sent up the tube with a whirling motion which 

 keeps the arc in the centre line. Each tube absorbs 1,000 H.P. The Badische 

 Anilinfabrik has combined with the Birkeland-Eyde Company, and altogether some 

 400,000 h.p. will shortly be utilised in Norway in the fixation of nitrogen. 



3. RAILWAY ELECTRIFICATION AND POWER TRANSMISSION 



The great progress made in the generation of electric currents on a large scale is 

 shown in the immense number of Power Stations now existing in the world, partly 

 hydroelectric or deriving their energy from water power, and partly coal-steam electric 

 stations. 



The hydroelectric stations have obtained much their greatest development in Can- 

 ada, Switzerland, Norway, Sweden, Italy, the United States, and other countries where 

 water power is abundant. The hydraulic arrangements depend essentially on whether 

 a low or high fall of water is available. If a high fall is utilised the power station may 

 be located at the lower level and the water brought down to it by large iron tubes from 

 an upper reservoir or lake. In this case the water motors, Pelton wheels or turbines, 

 are placed at the base of the fall pipes and discharge the water into a river or channel. 

 In other cases, such as Niagara, the turbines are placed at the foot of the penstocks and 

 a long shaft extends up to the power house at a higher level. The dynamos are in all 

 cases direct coupled to the water motors and may be direct current dynamos or single 

 or polyphase alternators. The cost of such a hydroelectric installation varies very 

 much according to the preliminary engineering work necessary to utilise the water, also 

 with the size of the water motor* units and whether the fall of water is low or high. In 

 round numbers it may vary from 25 per horse power of output for low falls to 5 with 

 high falls. An increase in the size of unit tends to economy. In the latest additions to 

 Niagara Falls power house the sizes of turbines installed are from 10,000 to 12,000 H.P., 

 whereas the earlier units were 5,000 H.P. size. 



The chief item of cost in connection with distribution of power electrically is the trans- 

 mission line. The reduced cost of aluminium has now made it economical to employ that 

 metal for conductors, since its specific gravity is one third that of copper and its electrical 

 conductivity only half as much again. The improvements made in high tension oil switches 

 and the control of large high tension currents, as well as in the construction of transformers 

 for raising voltage, have rendered it possible to transmit at voltages such as 60,000 or even 

 100,000 volts and thus economise in the size of conductors for a given power. Thus the 

 transmission of power from Niagara to Auburn, 163 miles, is carried out at 6p,ooo volts 

 by 3-phase currents over two lines, one of aluminium on wooden poles and one of copper on 

 steel towers. In California the Great Western Power Company have carried out a scheme 

 for the transmission of power electrically at a pressure of 100,000 volts over a distance of 

 several hundred miles. The Southern Power Company in the United States now distribute 

 at 100,000 volts over a distance of 164 miles. A line from Cook Falls in Michigan to Battle 

 Creek, 190 miles, is now operated at 135,000 volts, the power transmitted being 10,000 H.P. 

 or more. The Ontario Hydroelectric Commission recently placed contracts for 300 miles 

 of 110,000 volt transmission line. In Europe there is at least one 110,000 volt transmission 

 line in Saxony, the station being a steam-coal station in contiguity to a colliery, the owners 

 of which have agreed to supply power up to 12,000 kilowatts for 30 years. The transmission 



