Laws of Absorption of Liquids by Porous Substances. 503 



But the formeivresult is almost exactly double the latter : hence 

 it follows that the weight of water diffused through the upper 

 half of the 10-inch absorbent must have been very nearly equal 

 to the weight of water diffused through the lower half. 

 Let U = the work performed by absorption per minute. 

 k = the number of inches in one foot. 

 k x = the number of grains in one pound. 

 wf = the weight of water in grains diffused through each 

 inch of the absorbent. 



Then 



But w=VS 



S 



TxU -"2A X * l + \ 



(. 



v \ 2 w 



ok) x %qT; 



T-^and^gg; 



U: 



2kk\ T 14400^a 2 S 3 J 

 But for all appreciable values of S the fraction 

 is indefinitely small as compared with 1 ; 



I 



144<%*a 2 S 3 







which expression, being independent of S and T, is the same for 

 all points of ascent. Hence we infer that in equal times the force 

 of absorption performs the same amount of work. 



Experiment VII. 



The absorbent used in this experiment was fine calico, 2 inches 

 in width, and uniform in its texture. The temperature was 56° 

 throughout the experiment. As in the preceding experiments, 

 the liquid was distilled water. 



In this case the velocity of ascent is expressed by the formula 



1 



v= 



2-24S* 



