New York Agricultural Experiment Station. 275 



INTRODUCTION. 



The following research forms part of, and is preliminary to, 

 an extended investigation to be carried on at this Station under 

 the direction of Dr. W. H. Jordan, on the metabolism of phos- 

 phorus and sulphur in the animal body. 



It is quite generally believed that phosphorus exists in plant 

 substances, partly in organic combinations as nucleo-proteids, 

 nucleins and lecithins and partly in inorganic forms, such as cal- 

 cium, magnesium (^^ and potassium phosphates. It is not difficult 

 to understand how this view of the occurrence of phosphorus in 

 vegetable tissue originated, since inorganic combinations form the 

 basis of supply to the growing plant and since it is in the ash that 

 we have chiefly studied the kinds and proportions of the inorganic 

 plant constituents. Starting with the assumption that a consider- 

 able proportion of the phosphorus in animal and human vegetable 

 foods is inorganic in form, our efforts have been directed towards 

 the elaboration of a method for separating and quantitatively esti- 

 mating, at least approximately, this form of phosphorus in vege- 

 table and animal feeding stuffs. 



It was also thought that, should the ratio of organic to inor- 

 ganic phosphorus vary greatly in the different vegetable products, 

 this fact might be made the basis of investigations as to the rela- 

 tive nutritive value of these products for specific purposes. 



Such investigations could be undertaken, however, only after 

 the evolution of a fairly safe method for the separation of inor- 

 ganic from organic phosphorus. 



DETAILS OF INVESTIGATION. 



TOTAL PHOSPHORUS. 



Before taking up the experimental details of the estimations of 

 inorganic phosphorus, determinations of total phosphorus were 

 made on a number of vegetable and animal products by both the 

 magnesium nitrate and the Neumann methods. The Neumafm 

 method was tried particularly because it is convenient for use on 

 large volumes of liquids — a condition which must be met in the 

 separations involved in this inquiry. 



Magnesium nitrate uiethod. — This method is essentially the same 

 as that used by the Association of Ofiicial Agricultural Chera* 



(1) Sherman. U. S. Dept. Agr., Office Expt. Stas., Bui. 121. 



