606 



PRINCIPLES OF CHEMISTRY 



which is unaffected by heat, 39 and may therefore serve as a fire- 

 resisting material, and was employed by Deville for the construction 

 of furnaces in which platinum was melted, and silver volatilised by the 

 action of the heat evolved by the combustion of detonating gas. The 

 hydrated lime, slaked lime, or calcium hydroxide, CaH 2 2 (specific 

 gravity 2'07) is a most common alkaline substance, employed largely 



&ia. 78. Continually-acting kiln for burning lime. The lime is charged from above and calcined by 

 four lateral grates, B, M. D, fire-bars. B. space for withdrawing the burnt lime. K, stoke- 

 house. M, fire grate. Q, R, under-grate. 



in building for making mortars or cements, in which case its bind- 

 ing property is mainly due to the absorption of carbonic anhydride. 40 



* 9 Lime, when raised to a white heat in the vapour of potassium, gives calcium, and 

 in chlorine it gives off oxygen. Sulphur, phosphorus, &c., when heated with lime, are 

 absorbed by it. 



40 The greater quantity of lime is used in making mortar for binding bricks or stones 

 together, in the form of lime or cement, or the so-called slaked, lime. For this purpose 

 the lime is mixed with water and sand, which serves- to separate the particles ol lime 



