ANTISEPTIC TREATMENT OF SOILS. 171 



tected the soil particles from solution, by waterproofing 

 them to a sufficient degree to affect fertility, the treated 

 soils should contain at least from 30°/° to 50°A more plant 

 food than the untreated. This should be especially the 

 case where citric acid is used as a solvent, since this acid 

 is supposed to extract only available plant food. Accord- 

 ing to the work of Pickering, more marked increases should 

 be obtained from heated soils than from those treated with 

 antiseptics. 



The following are the soils examined : — 



1. A red sandy loam from the Grafton Experiment Farm — ■ 



very fertile and containing 8°/° volatile matter. 



2. A red heavy loam derived from andesite and ironstone 



on the Bundarra road five miles from Armidale — rather 

 sour and infertile ; 9°/° volatile. 



3. A red loam derived from conglomerate on the Bundarra 



road, four miles from Armidale — sweet and fertile, 

 containing 12°/° volatile matter. 



4. A black basaltic soil from Kelly's Plains, near Armidale 



— very rich and fertile, and containing 12°/° volatile 

 matter. 



5. An alluvial soil from the Gloucester River, North Ooast 



— very rich and fertile and containing 13°/° organic 

 matter. 



6. A drift soil from the old Nepean alluvials southeast of 



Penrith — very poor barren country, containing 2°/° 

 volatile matter. 



In the following tables (a) denotes determinations made with special 

 precautions to ensure absolutely pure precipitates, such as repaated pre- 

 cipitations of the iron to remove traces of lime, and the removal of 

 manganese from the lime precipitate etc.; whereas (b) denotes deter- 

 minations made without such special precaution. 



