46 



Journal of Agricultural Research 



Vol. IV. No. I 



FORMS OF NITROGEN PRESENT 



In order to estimate accurately the value of nitrogenous substances, 

 more than a mere statement of the percentage of nitrogen is necessary. 

 All compounds of nitrogen are not of equal worth, especially in nutri- 

 tion. Experiments were therefore undertaken to determine the general 

 forms of nitrogen present in the kelp. Water-soluble nitrogen, alcohol- 

 soluble nitrogen, and nonprotein nitrogen by Stutzer's reagent, also by 

 phosphotungstic acid, were estimated. Extractions were made on dried 

 and finely ground samples. An important part of the nitrogen (from 

 one-fifth to one-third) is soluble in cold water. (See Table IV.) About 

 the same proportion is classed as nonprotein nitrogen, using the methods 

 just mentioned. Other experiments, in which fresh kelp was leached, 

 showed similar relations for soluble and insoluble nitrogen. The water 

 extracts from a number of samples of ground kelp were analyzed for 

 acid amid and ammonia nitrogen, using the method of Abderhalden. 

 Protein nitrogen was precipitated by means of phosphotungstic acid, 

 the filtrate boiled in an 8 per cent solution of hydrochloric acid and dis- 

 tilled in the presence of an excess of magnesium oxid. In all cases the 

 amount of nitrogen so estimated v.-as insignificant. 



Table IV. — Forms of nitrogen in kelp 



Material used. 



Percentage of dried and 

 ground sample. 



Total 

 nitro- 

 gen. 



Nonprotein 

 nitrogen. 



By 



Stut- 

 zer's 

 rea- 

 gent. 



By 



phos- 

 pho- 

 tung- 

 stic 

 acid. 



Water- 

 solu- 

 ble 



nitro- 

 gen. 



Alco- 

 hol- 

 solu- 

 ble 

 nitro- 

 gen. 



Percentage distribution 

 of nitrogen. 



Alco- 

 hol- 



solu- 

 ble 



nitro- 

 gen. 



I. 2 



1-3 



9.1 



9-3 



29. I 



29. 2 



30. 1 



Macrocystis pyrifera No. i, harvest- 

 able leaves 



Macrocystis pyrifera No. i, harvest- 

 able stems 



Macrocystis pyrifera No. i, nonhar- 

 vestable leaves 



Macrocystis pyrifera No. 9, harvest- 

 able leaves 



Macrocystis pyrifera No. 9, nonhar- 

 vestable leaves 



Pelagophycus porra. No. 4, leaves. . . 



Pelagophycus porra No. 4, harvest- 

 able stem 



Nereocystis luetkeana No. i, leaves. . 



Nereocystis luetkeana No. 2, leaves. . 



Nereocystis luetkeana No. 3, leaves. . 



Nereocystis luetkeana No. 3, stem. . . 



Nereocystis luetkeana No. 4, leaves . . 



Egregia tnemiesii No. 3, complete 

 strands 



Laminaria andersonii, entire plants. 



Iridaea spp., entire plants 



I. 69 



2. 40 

 1. 01 



1. 62 

 1.24 



.98 

 1.86 

 1.90 



2. 20 



1. OS 

 1.97 



2. 7S 

 2.38 

 2.67 



36 



10. 7 



12. 2 



13-3 



6.0 



6.2 

 14- S 



7-1 

 18.8 

 22. 6 

 21.3 

 14-3 



16. 2 

 8.7 



13-4 

 13-5 



