Jan. 6, 1919 Determination of Acidity and Nitrogen in Wheat 7 



Figure 2 shows the results of titrating to Ph 8.3. At 5° the amount 

 of standard alkaH required increases very slowly. At 20° the increase is 

 very rapid up to four hours, followed by a gradual increase up to 24 

 hours. At 40° the increase is most rapid up to four hours. After that 

 the increase is slight or practically none. The final results at 20° and 

 40° are not much different. 



Figure 3 shows the results of titrating to Ph 9.3. The general direc- 

 tion of the curves are similar to those in figure 2, except that the values 

 are higher. 



DETERMINATION OF NITROGEN IN AMINO FORM BY FORMALDEHYDE 



METHOD 



Some investigators neutralize to litmus ^ and others to phenolphthalein ^ 

 before adding the formaldehyde. In Table I the results obtained by 

 neutralizing to three points: Ph 7, Ph 8.3, and Ph 9.3, are given. That 

 the latter two are the points of color change for phenolphthalein and 

 thymolphthalein, respectively, in these extracts, was determined ex- 

 perimentally. At Ph 9.3 the formaldehyde was added and then the 

 titration repeated until the concentration was again Ph 9.3. The 

 results of this last titration are given in the last column of Table I. 

 The amounts given times 0.7 gives the milligrams of nitrogen in the 

 amino form. If the formaldehyde had been added at Ph 8.3 and then 

 the titration continued to the Ph 9.3, a larger amount of NI20 barium 

 hydroxid would have been neutralized. Still larger amounts would 

 have been neutralized if the formaldehyde had been added at the strictly 

 neutral point, Ph 7, and then the titration continued to the Ph 9.3 

 point. These amounts are given in Table II, which has been calculated 

 from Table I. 



Table II. — Quantity {in cubic centimeters) of NI20 barium hydroxid required had the 

 neutralization been made to the points indicated before tlw formaldehyde was added 



Duration of extraction. 



5 minutes. . 

 30 minutes . 



1 hotir 



2 hours 



4 hours 



8 hours 



16 hours. . . . 

 24 hours. .. . 



First neutralization to Ph 8.3. 



5° C. 20° C. 40° C. 



Cc. 



3-0 

 2.9 



5-7 



Cc. 



3-4 

 4-7 

 5-9 

 7.0 

 7.6 

 8.6 

 9.4 

 10.5 



Cc. 

 3-2 

 6.6 



8-3 

 9.1 

 9.2 

 9.9 

 10. o 

 10. I 



First neutralization to Ph 7. 



5°C. 20° C. 40° C 



Cc. 



3-8 

 4. I 

 4.0 



9-7 



Cc. 



4-7 



6.7 



9. I 



10.8 



^3-3 



15-3 



20. 3 



22.8 



Cc. 



5-2 

 10. 6 

 15.0 

 18.5 

 21.3 

 22. I 



23-9 

 21. 4 



■ Allen's Commerciai, Organic Analysis, v. 8, p. 479. Philadelphia, 1918. 



» AbDERHALDEN, E&III,, ED. HANDBUCH DER BIOCHEMISCHEN ARBEITSMETHODEN. Bd. 3, HiilftC I, p. 228. 



Berlin, Wien, 1910. 



