140 PROCEEDINGS OF SECTION B. 



In the Continuous furnace care is taken to exclude air with a 

 view to making the electrodes last longer. The price of electrodes is, 

 however, much cheaper than in former years. They can be obtained 

 for about 35s. a ton. 



Rotating Furnace. 



The rotating furnace consists of a wheel about 20 feet in 

 ■diameter, which has an annular rim 3 feet in diameter. This rim 

 forms tlie furnace, and it is closed in by semi-circular slats, which are 

 readily removable. Only the lower half of the furnace has the rim 

 completed with its slats. 



The carbon electrode hangs down into the centre of the rim, and 

 as the carbide is made, the slow rotation of the wheel recedes it away, 

 thus leaving room for new material. The rim becomes filled with a 

 solid core of carbide, surrounded with some imcombined material. 

 When the wheel has turned sufficiently to bring this carbide to the 

 side of the wheel opposite to the electrode, the slats are taken off and 

 the carbide removed. 



One of the great advantages of the i-otating furnace is that no 

 automatic adjustment of the carbon electrode is necessaiy. The I'ota- 

 tion of the funiace and the supply of raw material are automatically 

 controlled by an electric motor in such a way as to keep the current 

 steady. About five days are required for the wheel to make a complete 

 revolutibn. 



Calcium Cyanimide. 



Tlie employment of carbide of calcium for the manvifacture of 

 the fertiliser cyanimide is an important development, and it will 

 probably result in more carbide being used for that purpose than for 

 acetylene lightfng. 



The manufacture of fertilisers will gain more and more import- 

 ance with time, because at the present increasing rate of consumption 

 the Chili nitrate deposits will become exhausted in about thirty years. 

 In twelve years, from 1896 to 1907, the consumption of Chili nitrate 

 iucrea^sed by 75 per cent., and the yearly rate of consumption is now 

 approaching 2,000,000 tons. 



There are two reasons for this : The number of wheat-eaters in 

 the world is steadily increasing, whilst the virgin land is as steadily 

 decreasing. A few years ago the United States could take crops off 

 her virgin lands without manuring, bvit the natural nitrogen in the 

 soil has now become exhausted, and fertiHsers have to be used. 

 Tliis Avill also take place with Australia's virgin soil. 



In 1906 Australia imported Chili nitrate to the value of £36,000, 

 the average price being a little over £10 per ton. With the increase 

 of land under cultivation for wheat and cereals, and the intense culture 

 which must follow the building of Barren Jack and Trawool dams, the 

 demand for fei-tilisers will eventually be very considerable. 



The discoveiy of calcium cyanimide resulted from an experiment 

 by Bunsen and Playfair, when they obtained cyanides by passing 

 nitrogen across a hot mass of carbon and alkalies. Professor 

 Frank, of Charlottenberg, and Dr. Caro repeated the experiment, and 

 found that the production of cyanide was preceded by the formation 



