MONAZITE, NICKEL 223 



Monazite contains many useful elements, among the best 

 known at present being Thorium and Cerium, both of which 

 are used in the making of incandescent mantles. 



After much labour, and many experiments, it was found that 

 a little mesh of cotton, soaked in a solution containing nitrate 

 of thorium, and a very small proportion of nitrate of cerium, 

 burned with an intensely bright light, and after many more 

 experiments the modern incandescent mantle was produced. 



Instead of cotton, ramie fibre is now generally employed. 

 A small cylinder of ramie net is soaked in the solution until 

 it is completely saturated. It is then wrung out and drawn 

 together at one end by an asbestos thread ; a loop of the same 

 material is added. The ramie is then burnt off and a very 

 delicate network of the oxides of the metals is left behind. 

 This is strengthened by being dipped in collodion, 1 which 

 in its turn is burnt off, after the mantle has been placed in 

 position on the gas-burner. 



Not only gas, but oil is used with incandescent mantles. 

 For instance, the Bell Rock Lighthouse, ten miles out at sea 

 from Arbroath, is lit by oil lamps having incandescent burners. 

 These throw a light across the waters equal in brilliance to 

 that of many million candles, and it is interesting to remember 

 that the intensity of this light is due to a large extent to 

 the elements thorium aud cerium. 



Cerium also helps to produce the brightness of searchlights, 

 and it is useful in many other ways. 



NICKEL is a hard silvery- white metal, and a small propor- 

 tion of it added to steel makes the latter exceedingly tough, so 

 that nickel steel is used when especial toughness and strength 

 are required. It is also lighter than ordinary steel. Armour- 

 plates, and parts of motor-cars, and burglar-proof safes, and 

 various munitions of war are made of it. 



Another valuable property of nickel besides its hardness 



1 Cotton soaked in nitric and sulphuric acid becomes highly explosive 

 and is called gun-cotton. Collodion is gun-cotton dissolved in ether or 

 alcohol. 



