Fig. 5 

 K & 



K 



134 Mr. T. Tate's Experimental Researches on Absorption. 



sure, the decrements of the rate of transmission vary directly as 

 the column of liquid equivalent to the reduction of pressure. 



Let K E C (fig. 5) represent a U-tube filled 

 with water; KB a siphon-filter, saturated 

 with moisture, placed on the orifice K in 

 contact with the water, a small weight being 

 laid upon the end of the filter to keep it 

 in position : then the water being discharged 

 by the siphon-filter causes the liquid to 

 descend on the side C D of the tube, so that 

 the reduction of pressure on the filter at 

 any instant is measured by the column of 

 descent C D. The rate of discharge is gene- 

 rally expressed by the formula 



v = a — bh, 



where v represents the velocity of discharge per minute, corre- 

 sponding to h the descent of the column CD. When h = 0, 

 v = a, which is the initial velocity; and bh is the decrement of 

 velocity due to the descent h, which is proportional to h. 



The formula closely expressing the results of experiment was 

 found to be 



*;=-35--05A; 



so that for A = l, 2, 3, 4, 5, 6, the corresponding values of v are 

 •3, *25, *2, -15, -1, and '05 respectively; but by experiment 

 these velocities were found to be *3, *25, *19, '14, *1, and '055 

 respectively. 



When the extremity B of the filter is inserted in a large vessel 

 of water, and the length K B of the filter is less than the depth 

 C D of the column, the current of the water is reversed ; that is, 

 the water is transmitted through the pores of the filter into the 

 tube, and the water D will rise in the tube. When the absorbent 

 is horizontal, the following law of transmission obtains : — 



7. When an absorbent transmits water into a closed vessel or 

 tube containing water under a reduced pressure, the rate of 

 transmission varies directly as the column of liquid measuring 

 the reduced pressure ; that is, the rate of transmission, the length 

 of the absorbent being constant, is expressed by the formula 



v = bh; 



where v is put for the rate at which the water is transmitted per 

 minute at the corresponding depth h of the liquid measuring the 

 reduction of pressure, and b a constant depending on the size 

 and nature of the absorbent, and the relative dimensions of the 

 essential parts of the apparatus. 



