94 



THE DATE PALM. 



The surface crust showed the following composition: 



TABLE 30. Per cent of alkali soluble in excess of water in surface crust, Station No. 3, 



Ourlana, Algeria. 1 



Calcium sulphate 3. 23 



Magnesium sulphate 03 



Magnesium chlorid 49 



Sodium chlorid 1. 20 



Potassium chlorid 07 



Sodium bicarbonate . . .12 



Total 



The following table shows the amount of alkali in the soil: 



TABLE 31. Per cent of alkali in soil, Station No. 3, Ourlana, Algeria. 1 



!Mr. Seidell's original analyses of the samples from this station are as follows: 



This soil is unique among those analyzed in showing a slight but evident increase 

 in the alkali content, especially of the harmful chlorids, as the depth increases and 

 a predominance of magnesium chlorid over the other chlorids in the upper layers 

 of the soil. 



Mr. Seidell called the writer's attention to the influence of the composition of the 

 irrigating water on the nature of the alkali. 



The rather unusual occurrence of chlorids of the alkaline earths in the water 

 which contains magnesium chloride to the amount of 0.069 per cent is paralleled by 

 the occurrence of the same salts in large amounts in all the surface crusts from Our- 

 lana. There can be no doubt that the composition of the alkali as it now exists in 

 the soil of the date orchards of Ourlana is profoundly influenced by the alkali left in 



