New York AGRICULTURAL EXPERIMENT STATION. 193 
were still visible, though rendered rather indistinct through 
diffusion. | 
The fact that these colored bands moved successively down- 
ward through the sand is clear evidence that the added liquids 
displaced the liquids already contained by the sand, and that 
diffusion did not take place during the process to any great extent. 
3. In another experiment a glass cylinder eighteen inches long 
and five inches in diameter, closed at its lower end as already 
described, had its inner walls dusted with a little of the indicator 
named above, after which it was filled with emery flour and the 
latter saturated with water. A little dilute solution of potash 
was then added at the upper end of the cylinder. The crimson 
color produced by the action of the potash on the indicator first 
appeared at the top, and passed downward regularly, as long as 
any of the solution remained above the emery. When the latter 
had all disappeared, however, the downward movement ceased 
until more was added. This process continued until the bottom 
of the cylinder was reached by the colored band, but not a drop 
of the colored liquid passed off, as percolation, previous to this 
_time. The amount of the percolation before the potash appeared 
was somewhat greater in this case than the amount of water 
contained by the emery flour, showing clearly that the potash 
solution did not come through until it had first forced out the 
water contained by the emery flour. 
4, Other tests were made, using nitrate of soda, sulphate of 
copper and common salt, adding dilute solutions of these 
substances to columns of sand and detecting their appearance in 
the percolation by means of indicators, with similar results. 
5. In a later experiment, the attempt was made to measure the 
actual per cent of displacement in the case of the white sand used 
in the trial first described. The wet sand in the tube was replaced 
by dry, and just beneath the center of the bottom of the tube, was 
secured a piece of filter paper, upon which was placed a bit of the 
indicator named above. A measured quantity of water was then 
added at the top of the tube, and after the percolation had ceased, 
the quantity percolated was measured, to ascertain the amount 
of water retained by the sand. The same quantity of a one 
per cent solution of potash was next added by means of a 
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