398 



Journal of Agricultural Research 



Vol. XV, No. 7 



centage was obtained, and boiled under reflux for a definite time. No. 

 I and 2 were then neutralized with sodium hydroxid, and on addition 

 of 3 gm. of magnesium oxid were subjected to distillation, while No. 

 3 to 14 were directly distilled with 3 gm. of magnesia. The results are 

 recorded in Table VII. 



Table VII. — Hydrolysis of asparagin with hydrochloric acid 



No. 



Strength of 



hydrochloric 



acid. 



Boiled under 

 reflux. 



Ammoniacal nitrogen found. 



Observed. 



Average. 



Per cent. 



1 . 



2 . 

 3- 

 4- 



s- 



6. 



7- 

 8. 



9- 

 10 

 II 

 12 

 13 

 14 



20 

 20 



Hours. 



K 



Algm. 



11-43 

 II. 50 

 Lost. 

 II. 61 

 12.34 

 12.05 



11. 92 



12. 22 

 12. 27 

 12.36 

 12. 36 

 12.44 



Per cent. 



47-53 

 43- 6& 



44.22 

 46. 46 



45-97 

 46. 92 

 47.22- 



From the table it follows that boiling asparagin with 4 per cent hydro- 

 chloric acid for 2 hours split off, in the form of ammonia, as much nitro- 

 gen as did boiling with 20 per cent hydrochloric acid for 30 minutes. 



DESCRIPTION OF METHODS 



(i) The total soluble nitrogen, as mentioned already, was usually estimated in 

 25-cc. portions of the aqueous spinach extract according to the Gunning modification 

 of the Kjeldahl method. 



(2) The nitrogen of ammonia present as such in the spinach materials was esti- 

 mated according to Grafe's method {14), which is based upon the work of Wurster, 

 Boussignault, Folin, Kriiger, and Reich. Ordinarily 20 gm. of air-dry spinach were 

 introduced into a 2 -liter round-bottom flask with the aid of 50 cc. of saturated sodium- 

 chlorid solution, 50 cc. of distilled water, 25 cc. alcohol, and the whole mixed thor- 

 oughly. The flask was then connected with a Peligot tube (of about 400 cc. capacity) 

 usually containing 20 cc. of N/^ sulphuric acid, whereupon 25 cc. of saturated sodium- 

 carbonate solution were added . After the whole apparatus was carefully made air-tight, 

 the burner under the water bath was lighted and the suction pump (May-Nelson) 

 brought into action. The first 3 hours the distillation took place at 25° to 28° C, the 

 last 3 or 4 hours at about 37°. The absolute pressure observed was mostly about 20 mm. 

 (ranging from 5 to 45 mm.). The ammonia found in the spinach bj' this method 

 was taken to represent also the ammonia in the aqueous spinach extract. A direct 

 ammonia determination in the spinach extract, because of the heat applied at the 

 extraction, was deemed inaccurate. 



(3) The acid amid nitrogen was estimated in 250-cc. portions of the spinach 

 extract. The latter, on hydrolysis, was evaporated to dryness, transferred quanti- 

 tatively to an Soo-cc. Kjeldahl flask of Pyrex glass with the aid of 100 cc. of distilled 



