[ 569 ] 



io million parts. The result of an actual analysis of a 

 sample of well water is given below: 



N ... ... 150 parts in io million parts. 



P 2 O 5 ... 100 J 



K 2 O ... 100 ; ,, 



CaO ... 1,000 - 



MgO ... 1,000 



Na 2 O ... 3,000 



94^. Well and canal water which are known to be harm- 

 ful to vegetation, contain a larger excess of MgO and Na 2 O, 

 ie. 6,000 or 7,000 parts of each in io million parts. Canal 

 water rarely contains such excess, but well water often does. 

 Hence the unsuitability of some well waters for irrigation 

 and the belief current among Bengal cultivators of the general 

 unsuitability of well water for irrigation, 



CHAPTER XCII. 



OYPSUM AND SAI/r. 



/ ' ^YPSUM occurs in the natural state in the following loca* 

 lities: at Trichinopoly, Nellore and Chingleput in Madras; 

 in the latter two places as crystals of Selenite; in Cutch and the 

 Kirtha range of Sind in Bombay ; near Nagore in the Jodhpur 

 State in Rajputana; at Bijawarand Baraundhain Central India; 

 at Bannu and Kohat and the Salt Range in the Punjab ; and in 

 Kumaoun and Garhwal in the N.-W. P. Burnt gypsum is used 

 as a cement. It is a valuable manure chiefly for leguminous 

 plants, though it is not used in India. The Salt Range in 

 the Punjab is overlaid by a deposit of gypsum 15 to 20 ft. 

 thick, enough for , supplying the needs of the whole world. 

 The refuse from aerated water manufactories is artificial 

 gypsum. It should be used mixed up with lime asjt is liable 

 TTT 



