170 H. I. JENSEN. 



and more water soluble organic matter than untreated soils. 

 The increase of soluble matter in the treated soils is not 

 great but it is definite. His tables show that the increase 

 of water soluble organic matter greatly exceeds the in- 

 crease of water soluble salts. 



In 1910 1 and Jan. 191 V Dr. Greig-Smith read papers in 

 which he maintained that the increased fertility of treated 

 soils is due to heat and antiseptics having the effect of 

 removing from the soil particles an organic fatty substance* 

 termed by him 'agricere,' which he supposes to waterproof 

 the particles and to prevent the assimilation of plant food. 



If this is the correct explanation of increased fertility 

 due to heating or antiseptic treatment of soil there should 

 be a marked increase in soluble plant food of heated and 

 treated soils as compared with untreated ones. 



Pickering shows a slight increase in the water soluble 

 material of heated and treated soils as compared with the 

 same soils not treated, but his figures hardly show suffici- 

 ently marked increases to account for the great increase 

 in fertility noticed by Russell and Hutchison. 



If Dr. Greig-Smith's theory be correct the increase in 

 the amounts of fertilising constituents should be even more 

 marked when stronger solvents than distilled water are 

 used, for the agricere would tend to protect the soil par- 

 ticles from the action of citric acid, hydrochloric acid or 

 nitric acid. At any rate one would expect noticeable 

 results from the citric acid treatment. 



Analyses were undertaken with a view of testing whether 

 this is the case or not, and the results are given in the 

 following tables. It was expected that if agricere pro- 



1 Proc. Linn. Soc. N.S.W., 1910. 

 2 Austr. Assoc, for Adv. Sci., Sydney Meeting, 1911. 



