REFERENCES 



1. Venable : History of Chemistry. 



2. Gilbert : Inaugural Lecture, University of Oxford. 



3. Liebig : Chemistry in Its Applications to Agriculture and 

 Physiology. 



4. Gilbert: The Scientific Principles of Agriculture (Lecture). 



5. Minnesota Agricultural Experiment Station, Bulletin No. 30. 



6. Stockbridge : Rocks and Soils. 



7. Association of Official Agricultural Chemists, Report 1898. 

 Note : — This sentence should read : A division has recently 



been suggested by Hopkins in which the square root of ten is 

 taken as the constant ratio between the grade of soil particles. 



8. Maryland Agricultural Experiment Station, Bulletin No. 21. 



9. Osborne : Journal of Analytical Chemistry, Vol. II, Part 3. 



10. Wiley : Agricultural Analysis, Vol. I. 



11. Hellriegel : Calculated from Beitrage zu den Naturwissen- 

 schaft Grandlagen des Ackerbaus. 



12. King : Wisconsin Agricultural Experiment Station, Report 

 1889. 



13. Unpublished results of author. 



14. King : Soils. 



15. Roberts : Fertility of the Land. 



16. Minnesota Agricultural Experiment Station, Bulletin No. 41. 



17. Minnesota Agricultural Experiment Station, Bulletin No. 53. 



18. Whitney : Division of Soils, U. S. Department of Agriculture, 

 Bulletin No. 6. 



19. Merrill : Rocks, Rock-weathering and Soils. 



20. Muntz : Comptes Rendus de l'Academie des Sciences, CX 

 (1890). 



21. Storer : Agriculture, Vol. I. 



22. Dyer : Journal of the Chemical Society, March, 1894. 



23. Goss : Association of Official Agricultural Chemists, Report 

 1896. 



