176 



Soil Analysis 



[299 



C0 2 in limestones, as this may be calculated from the per- 

 centages of lime and magnesia, and the analysis is stated as 

 follows : 



Combined water, alkalis, &c. 



CaC0 3 . 



MgC0 3 . . 



Fe„0 3 and A1 2 3 



P 2 O s . . 



Silicates . 



Nottinghamshire 

 dolomite 



5-34 



54-54 



38'35 



•48 



•08 



I -21 



ioo-oo 



Derbyshire 

 mountain limestone 



•22 



97'35 

 71 

 •09 



1-63 



ioo-oo 



ANALYSIS OF LIME 



299. This analysis is carried out in exactly the same way 

 as the analysis of limestone, except that it is usual to estimate 

 the C0 2 and the combined water present. The C0 2 may be 

 estimated by one of the methods described in paragraphs 



5°-56. 



Combined Water. Weigh out about 2 grams of the lime 

 into a platinum dish, and place in a Fletcher muffle furnace 

 (fig. 17), heated to a bright red for twenty minutes. Allow 

 to cool to a dull red ; remove to a desiccator, allow to cool 

 thoroughly, and weigh. The loss of weight represents the 

 quantity of C0 2 and combined water present. By subtracting 

 C0 2 we obtain the amount of water combined with the CaO 

 in the form of Ca(HO) 2 . 



ANALYSIS OF GAS LIME 



The only difference between this and the analysis of 

 lime is that in gas lime the sulphur must be estimated. Now, 

 this sulphur exists in three forms — viz., sulphate of calcium, 

 sulphite of calcium, and sulphide of calcium. It is usual to 



