2 Journal of Agricultural Research voi. xvi. No. i 



METHOD OF MAKING THE EXTRACT 



A good grade of Kansas hard wheat was used for this work. The 

 wheat was finely ground, untempered in a burr mill. Fifty gms. of this 

 ground material were weighed into a quart Mason jar and heated to the 

 temperature used in making the extraction. Five hundred cc. of carbon- 

 dioxide-free water, previously heated to the temperature employed, 

 were then added, together with 5 cc. of toulene as a preventive of bac- 

 terial action. The whole was thoroughly shaken and placed in a 

 thermostat. The shaking was repeated every minute for the first 5 

 minutes, then every 15 minutes during the time of extraction. At the 

 end of the extraction period the contents of the jar were poured into 

 centrifuge cups and centrifuged for 5 minutes at 2,000 revolutions per 

 minute. The supernatant liquid was then poured through a filter for the 

 purpose of removing light floating particles. The filtrate was used for 

 the following determinations: 



1. The hydrogen-ion concentration or the Ph value of the extract. 



2. The cubic centimeters of NI20 barium hydroxid used to titrate to 

 the absolute neutral point of Ph 7. 



3. The cubic centimeters of alkali used to titrate to the point of color 

 change for phenolthalein or Ph8.3. 



4. The cubic centimeters of alkali used to titrate to the point of color 

 change for thymolphthalein or PhQ-S- 



5. The amount of alkali necessary to reneutralize after the addition 

 of neutral formaldehyde or the vSorensen method of determining amino 

 nitrogen. 



6. The total phosphorus in the extract. 



7. The phosphorus in the extract precipitated by magnesia mixture. 

 This may be considered phosphorus in the inorganic form. This method 

 of determination is based on that used for the determination of inorganic 

 phosphorus in animal tissues. 



APPARATUS USED IN DETERMINING HYDROGEN-ION CONCENTRA- 

 TION 



Our apparatus contains the following pieces: One Kohlrausch slide 

 wire bridge; one type B, No. 2500 Leeds and Northrup galvanometer; 

 one Weston millivoltmeter and multiplier; Edison storage cells; and the 

 hydrogen and the normal calomel electrodes made according to the 

 directions of Hildebrand.^ Hydrogen made by the electrolytic process 

 was used. As a precaution against impurities, the gas was washed in a 

 train of alkaline permanganate and pyrogallic acid. 



1 HlLDEBRAND, JOEL H. SOME APPLICATIONS OP THE KA'DROGEN ELECTRODE IN ANALYSIS, RESEARCH, 



AND TEACHING. In JouT. Amer. Chem. Soc, v. 35, no. 7, p. 847-871, 15 fig. 1913- 



