LIME 193 



LABORATORY EXERCISES 



Exercise I. — A study of the forms of lime. 



Materials. — Set of lime samples (ground limestone, marl, quick- 

 lime, hydrate of lime and gypsum), hand lens, muriatic acid, litmus 

 paper. 



Procedure. — Study the various forms of lime until identifica- 

 tion is easy. 



Ground Limestone and Marl 



Ground limestone can be detected by its physical condition, es- 

 pecially if a hand lens is used. It is practically insoluble in water. 

 Its color varies from white to gray. The presence of carbonates 

 may be detected by a few drops of dilute muriatic acid. 



Marl is a soft powdery form of calcium carbonate. Its texture 

 and the presence of shells and organic matter serve to distinguish 

 it from ground limestone. 



Quick-lime 



Quick-lime appears on the market either in lumps or as a fine 

 powder. It is very caustic and intensely alkaline to litmus paper. 

 When in contact with water it heats and slakes, becoming hydrate 

 of lime. This characteristic distinguishes it from the other forms 

 of lime. 



Hydrate of Lime 



This form of lime is a white powder, soluble in water. Its sour 

 taste serves to distinguish it from marl and limestone. It is alka- 

 line to litmus paper. 



Gypsum 



This amendment is marketed as a grayish to white powder, in- 

 soluble in water. It is calcium sulfate. It does not react with acid 

 as does the limestone nor with water as does the lump lime. Its 

 lack of taste distinguishes it from hydrate of lime. 



Exercise II. — Fineness of ground limestone. 



Materials. — Samples of limestone, 10, 20, 40, 60 and 100 mesh 

 sieves, balance and weights. 



Procedure. — The fineness of ground limestone has a marked 

 effect on its value. Weigh out 100-gram portions of the various 

 samples of limestone and pass them through the sieves. Weigh 

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