126 BULLETIN No. 145 [April, 



49. NANNES, Zur Grabe iiber die Verbindungsformen der Phos- 

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 chemie: (1899), Band 42, S. 89. 



50. SNYDER, Available Plant-food of Soils. Minn. Agr. Exp. 

 Sta. : (1900), Bui. 65, p. 61. 



51. PAGNOUL, Humus and Carbon in Cultivated Soils. Exp. 

 Sta. Record: (1900), Vol. 13, p. 121. 



52. EM MERGING, Ueber die verschiedenen Formen der Phos- 

 phorsaure im Boden und deren Bestimmung. Biedermanns 

 Central-blatt fiir Agrikulturchemie : (1900), Band 29, S. 75. 



53. RIMBACH, Investigations on the Determinations and Compo- 

 sition of Humus and its Nitrification. Jr. Am. Chem. Soc. : 

 (1900), Vol. 22, p. 695. 



54. FREAR and HESS, Effects of Different Systems of Manuring 

 Upon the Amount and Quality* of the Humus in the Soil. Pa. 

 Agr. Exp. Sta. Kept. (1900-01), p. 173. 



55. DYER, Results of Investigations on Rothamsted Soils. Of- 

 fice of Experiment Stations: (1902), Bui. 106, p. 29. 



56. DOJARENKO, Der Stickstoff des Humus. Landwirthschaft- 

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57. NAGAOKA, On the effects of Soil Ignition upon the availabil- 

 ity of Phosphoric Acid. Exp. Sta. Record: (1904), Vol. 16, 



P- 555- 



58. Aso, Ueber das Vorkommen von Phosphorsaure in organ- 

 ischen Verbindungen im Boden. Biedermanns Central-blatt 

 fiir Agrikulturchemie: (1904), Band 34, S. 3. 



59. PETTIT and SCHAUB, The Determination of Organic Carbon 

 in Soils. Jr. Am. Chem. Soc.: (1904), Vol. 26, p. 1640. 



60. HARTWELL and KELLOGG, The Phosphorus associated with 

 the Organic Matter of the Soil. Rhode Island Agr. Exp. Sta. 

 Rept. (1904-05), p. 268. 



61. CAMERON and BREAZEALE, The Organic Matter in Soils and 

 Subsoils. Jr. Am. Chem. Soc.: (1904), Vol. 26, p. 29. 



62. DUMONT, Sur les engrais humiques complets. Compt. rend. : 

 (1904), tome 138, p. 1429. 



63. CAMERON, A Comparison of the Organic Matter in Different 

 Soil Types. Jr. Am. Chem. Soc.: (1905), Vol. 27, p. 256. 



64. DUMONT, Sur la valeur agri-cole des matieres humiques. 

 Compt. rend.: (1905), tome 140, p. 256. 



65. DUMONT, Les composes phospho-humiques du sol. Compt. 

 rend.: (1906), tome 143, p. 186. 



66. HALL and MILLER, The Nitrogen Compounds of the Funda- 

 mental Rocks. The Journal of Agricultural Science: (1908), 

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