ABSORPTION OF WATER. 



Strength of 

 solution 



Amount of 

 water absorbed 



Nitrate of ammonia, 

 o*735 P er cent - 5 c -c 

 0-0491 49 



0-0245 50 



Amount of 

 salt absorbed 



0-059 

 0-044 

 0'02I , 



Strength of 

 solution absorbed 



o'ii8 per cent. 

 0-089 

 0-042 



59 



Difference 



+ 0*0445 

 + 0-0399 

 + 0-0175 



It appears, therefore, that de Saussure's law is merely an 

 account of a special case. The law of absorption is rather 

 this: for the watery solution of any given salt capable of 

 being absorbed there is a certain degree of concentration 

 at which the proportion of the amount of the salt absorbed 

 to that of the water absorbed is the same as that of the 

 solution ; if the solution be more concentrated the proportion 

 of water absorbed will be greater, if the solution be more 

 dilute the proportion of salt absorbed will be greater. It must 

 not, however, be overlooked that although the proportion of 

 a salt absorbed is greater when the solution is dilute, the 

 absolute quantity of it absorbed in a given time is greater 

 when the solution is more concentrated. 



The foregoing figures suffice to shew that plants absorb 

 different substances in different proportions, but, should 

 further proof be needed, it will be found in the tables given 

 below to illustrate the discussion of the question as to whether 

 or not different plants absorb the various salts to the same 

 extent, that is, as to whether or not each plant is endowed 

 with what we may term a specific absorbent capacity. 



The fact that different salts are absorbed in different proportions is 

 well illustrated by analyses of water-plants. Thus, von Gorup-Besanez 

 analysed Trapa natans and the water in which it was growing : 



