New York Agricultural Experiment Station. 279 



Table II.— Comparison of Methods for Separation of Forms of 

 Phosphorus. 



Sub- 

 stance. 



Oats. 



Treatment. 



!%■ acetic 12 min. SS'^ C 



" '' room tern. 24 hours 



" " " " 40 " 



" " " " 3 " 



.2%' hydrochloric, room tern. 4ohrs 



•5% hydrochloric, 10 min. 55° C 



1% acetic, room tem. I7hr«. tannin 



.2%" hydrochloric, room tem. 17 hrs tannin. 



1% acetic 10 min. 55° C. tannin 



.2%' hydrochloric, 10 min. 55° C. tannin 



Total 

 phos- 

 phorus. 



Insol- 

 uble 

 organic 

 phos- 

 phorus. 



Per ci. 

 -355 



Percentage of phos- 

 phorus in air-dry 

 material. 



Per ct. 

 .210 

 .240 

 .227 

 .252 

 .258 

 .184 

 .094 

 .206 



•075 

 .223 



S.'luble 

 phos- 

 phorus. 



Per ci. 

 .142 

 .116 

 .138 

 -103 

 .092 

 .171 

 .244 

 .126 

 .240 

 .109 



Inor- 

 ganic 

 phos- 

 phorus. 



P,r ct. 



■035 

 042 

 .032 

 .017 

 .006 

 .014 



iv 3 »5 

 (^ ft a 



These results show how decided a variation may occur in the 

 quantities of the different forms of phosphorus as estimated under 

 \ar\ing- conditions of manipulation. They also show in certain 

 instances an apparent inorganic content appreciably large, while 

 in others practically none was found, indicating again the influ- 

 ence of certain varying factors in the method of separation. That 

 tannin fails to remove a large proportion of soluble organic forms 

 is also very evident. 



We next made the same separations with a number of mate- 

 rials, using, as the extracting reagents, 0.2 per ct. hydrochloric 

 and I per ct. acetic acid solutions for forty hours at room 

 temperature. The inorganic phosphorus was estimated by the 

 same method as that used in the case of oats. 



