174 H. I. JENSEN. 



It may be taken for granted from Pickering's researches 

 that there is a distinct increase in the water soluble organic 

 matter of heated and treated soils. This difference is 

 however, not large enough to account for the differences 

 in fertility described by Russell and Hutchison. 



The evidence is therefore decidedly in favour of the view 

 taken by Russell and Hutchison, that the increased fertility 

 is due to the destruction of the protozoa and nitric acid 

 producing bacteria and a quick revival of the ammonia 

 forming bacterial flora. 



While the work done fails to give any support to Dr. 

 Greig-Smith's theory of 4 waterproofing,' there is still a 

 strong possibility that 'agricere' or 'agrostearol' is a toxic 

 substance whose poisonous action is somewhat reduced by 

 heating or by the use of volatile antiseptics to remove it to 

 the aerated soil crust. 



In a recent paper by G. S. Fraps of the Texas Agricultural 

 Experiment Station it is stated that the acid soluble soil 

 phosphate is increased by ignition of the soil. Our work 

 has failed to give any evidence of the truth of this state- 

 ment, and Mr. Hargraves, Chief of the Chemical Agricul- 

 tural Laboratory of South Australia, verbally informed me 

 that in his department investigations had been made which 

 proved that ignition did not increase the amount of any of 

 the fertilising ingredients of soils extracted by acids. 



Mr. Fraps 1 shows that certain natural phosphate minerals 

 are rendered more acid soluble by ignition, but probably 

 these minerals are not abundant in our soils. In one 

 respect we can confirm the work of Mr. Fraps, namely, when 

 he states that the acid soluble iron and alumina of a soil is 

 increased by ignition. This has been frequently noticed in 



1 Journal of Industrial and Engineering Chemistry, May 1911, Vol. 

 in, No. 5. 



