64 F. B. GUTHRIE AND L. COHEN. 



There are one or two points to be noted in these tables. 

 In the first place the amount of mineral plant-food (phos- 

 phoric acid and potash) soluble in water has suffered a very 

 considerable decrease during the period of the experiment, 

 notably the water-soluble phosphoric acid in all soils, and 

 the potash in the clay soil. 



The action of liming has been in all cases to produce an 

 increase in the quantities of water-soluble plant-food over 

 the unlimed, but it is only in the sandy soil where liming 

 lias had the effect of increasing the proportions of water- 

 soluble phosphoric acid and potash above those originally 

 present in the soil. 



There was no vegetation in the pots, and no drainage 

 except through the walls of the pots, and the samples for 

 analysis were taken by mixing the whole of the contents 

 of the pots and not from the surface layer only. It would 

 therefore appear that there is a steady loss of water-soluble 

 plant-food during the period, either by percolation through 

 the sides of the pot or by conversion into insoluble plant- 

 food. Whether the lime present prevents this reversion of 

 the water-soluble plant-food, or whether it renders fresh 

 plant-food soluble in water is not shown by this experiment. 



In the case of the citric acid soluble ingredients there 

 has been very little appreciable alteration in the quantities 

 after standing, in some cases there has been an actual 

 increase. The effect of liming is much less marked than 

 with the water-soluble plant-food. In the case of the 

 phosphoric acid there is an actual decrease in this con- 

 stituent, especially in the clay soil. In the case of potash 

 the increase is also much less than with the water-soluble 

 potash, except in the case of the garden loam. 



Portions of the unlimed and limed soils were also 

 examined in order to ascertain the effect of lime on the 

 soluble nitrogen. The pots had by this time been standing 



