530 EXPERIMENT STATION RECORD. 



"Little change was wrought l>y the action of the solvents in the amounts of lime 

 and potash soluble in water. . . . We see, however, that the amounts of lime and 

 potash rendered soluble in 1 per cent citric aeid are enormous, even in compari- 

 son with the large proportions soluble in that solvent in the natural soil. There 

 are features in the behavior of the potash which attract special attention. It is 

 seen that less potash is found soluble in 1 per cent citric acid after the action for 130 

 days of the 1 per cent solvent than where the -^ per cent solvent was used. This 

 behavior is also repeated in the beaker series of experiments with the lowland soil. 

 Also the phosphoric acid gives peculiar results of the same nature. In every exam- 

 ple the soils acted upon for 130 days by the stronger solvents showed less phosphoric 

 acid soluble in 1 per cent citric acid after than before the action. These peculiar 

 results are bound up with the question of resorption." 



To further study the question of resorption the following experiments 

 were made: 



"As a first test a given volume of a solution, which had been obtained by treating 

 a soil with a dilute solution of citric acid, containing known amounts of given 

 elements, was passed through a new quantity of the same soil. A second test con- 

 sisted in passing another but a similar solution, which had been obtained by the 

 action of a dilute citric acid solution upon the soil, through a totally different 

 soil. . . . 



"In the first test the result of passing the solution through the same soil was 

 to increase its lime, to double its potash, and to reduce its phosphoric acid con- 

 tent. ... In the second test, despite the very high potash content of the second 

 soil, that soil took one-half of the potash out of the solution on its passing through; 

 also the same soil, although its content of phosphoric acid was only one-fourth as 

 large as that of the first soil, did not absorb any phosphoric acid from the passing 

 solution." 



Similar experiments on mixed soil are reported which show — 



"(1) That the result of continuing to pass the solution through the soil from 

 which it had been obtained was merely to dissolve out more of the several elements, 

 excepting phosphoric acid. 



"(2) [When the extract was neutralized with sodium carbonate before being 

 passed through the fresh soil there was] an emphatic absorption by the fresh soil of 

 all elements, notably of the lime, silicic acid, and iron. This is in particular agree- 

 ment with observations upon the action of dilute citric acid upon neutral soils in 

 distinction from the action of the same solvent on acid soils. 



"(3) In the absence of the carbonic acid, furnished by the carbonate of soda, the 

 lime and also the potash continue to increase in the solution when it is passed 

 through the fresh soil. But almost one-half of the silica and phosphoric acid are 

 taken out of the solution by the fresh soil with a notable amount of iron and 

 alumina, bases." 



The average composition of the water of discharge of the Hawaiian 

 Islands is given, and the losses from soils in drainage are discussed, 

 it being claimed that it is erroueous to assume that " the composition 

 of sea water represents the relative amounts of elements removed from 

 the land and carried into the ocean by water." 



A study was made in this connection of the relative proportion of 

 soil constituents soluble in 1 per cent solutions of different acids. The 

 results are given in the following table: 



