MOVKM KNTS OF SALTS IN SoII.S. 



95 



contratioii suck that larger absolute amounts of nitric acid 

 were recovered. 



To test this hypothesis, two soils were procured ; one a loamy 

 sand and the other a sandy soil, each containing at the time a 

 low per cent, of moisture. Bulk lots of both soils were screened 

 and thoroughly mixed, so that 'closely duplicate samples could 

 be obtained. Three sets of an apparatus represented in Fig. 6, 

 p. 95, were filled with the two kinds of soil. Each piece of 

 apparatus consisted of glass tubes, 2 inches long and seven- 

 eighths inch inside diameter, held together with rubber tubing 

 and closed at the lower end with a piece of muslin. 



CAPIUARY 



CHICS 

 CU1IDER 



--- UPPER SECTIOF --- 



--RUBBER BA*D ', 



- - LOWER SECTIOH . 



FIG. 6. Showing apparatus used in demonstrating the possibility of recovering 

 larger amounts of nitrates from soils by capillary sweeping than by agi- 

 tation or by percolation. 



When the cylinders were filled with these respective soils 

 they were placed in nitrate-free water until, at the end of 15 

 minutes, the soils became moist at the surface and capillarity sat- 

 urated. At this stage the two sections of the tubes were sepa- 

 rated and the amounts of nitrates in each determined at once, 

 obtaining the results which are given in the table which fol- 

 lows: 



