Aug. 13, 19x7 



Origin of Alkali 



343 



pounds of sodium chlorid, and 5,492 pounds of sodium nitrate per 

 2,000,000 pounds as an average of 23 determinations of alkali from 

 widely separated portions of the Cretaceous area — that is, in this crude 

 alkali material collected in the uncultivated soil there is 17.10 per cent 

 soluble in water. 



In our previous publications (9, 10) attention was called to the fact 

 that the niter spots were not characteristic of cultivated irrigated soil, 

 but were found in the virgin condition wherever the moisture condition 

 was suitable for a concentration of the salts. Special attention was 

 directed to one such spot, as represented by samples 130, 131, 132, and 

 133, representative of the shale, soil, alkali, and ash, respectively. Now 

 that the complete data are available, it is interesting and instructive to 

 study these samples again. The complete data are given in Table VI. 



Table VI. — Soluble salts in material from a native niter spot 

 [Results expressed as pounds per 2,000,000 of material] 



In this characteristic niter spot occurring in the virgin soil we find that 

 the accumulations of nitrates are accompanied by accumulations of other 

 soluble salts such as the chlorids and sulphates of calcium, magnesium, 

 and sodium. The parent shale contains 4.75 per cent of soluble salts, 

 over one-half, or 52.4 per cent, of which is sodium sulphate; 10 per cent 

 of calcium bicarbonate; 0.51 per cent of sodium chlorid; 0.94 per cent 

 of sodium nitrate. In the soil derived from this shale there are 3.23 per 

 cent of soluble salts in which the sulphates of sodium and calcium are 

 about equal — that is, 45.4 per cent is sodium sulphate, 44.2 per cent is 

 calcium sulphate, 8 per cent magnesium sulphate, 1.65 per cent cal- 

 cium bicarbonate, i.io per cent sodium chlorid, 1.17 per cent sodium 

 nitrate. In the alkali there are 45.5 per cent of total soluble salts with 

 a marked increase in the chlorid, sulphur, and nitrate of sodium. Of 

 the total soluble material 48.6 per cent is the sulphate of sodium, 32.1 

 per cent is the chlorid of sodium, 7.4 per cent is the nitrate of sodium, 

 6.05 per cent is the sulphate of magnesium, 5.13 per cent is the sulphate 

 of calcium, while the bicarbonate of calcium is entirely missing. In 

 fact, the aqueous extract of the alkali is acid to methyl orange. The 

 ash contains 12.78 per cent of soluble salts, of which 50.9 per cent is 

 the sulphate of sodium, 12.6 per cent is the sulphate of calcium, 5 

 per cent is the sulphate of magnesium, 25.5 per cent is the nitrate of 



