538 
Journal of Agricultural Research 
Vol. XXVIII, No. 6 
The results obtained for ammoniacal nitrogen by the modified Strowd method 
show that it is necessary to filter the solution, after which the aliquot for the 
control can be used for the ammonia determination. In fact the duplicates 
agree as well as the determinations made by different analysts by the official 
method on the same sample. 
The distillation with magnesium oxid for ammoniacal nitrogen often gives 
high results on materials containing organic nitrogen. As the averages obtained 
by the modified Strowd method for this determination agree with the official 
procedure consequently they together with the nitrate results indicate that it 
is possible to make a satisfactory estimation of both ammonia and nitrate on the 
same solution provided a filtered aqueous extract of the sample is employed. 
If only the nitrate is desired, filtration will probably not be necessary although 
it may be desirable under different conditions. 
The writer does not recommend the modified Strowd procedure for all nitrate 
determinations until further work establishes its reliability for the purpose. At 
the same time, it is believed that it will be found useful for samples of a different 
nature from those employed in this investigation. s 
SUMMARY 
1. A comparison has been made of a Devarda alloy method published by Strowd 
for the determination of nitrates in plants and a modification of same in which 
it was found advantageous to let the reduction continue for twenty-four hours 
at room temperature, previous to heating the solution. 
2. Both procedures show a fairly complete recovery of considerable amounts 
of pure nitrate in solution and of nitrate added to tobacco of a low nitrate con¬ 
tent. 
3. More concordant and generally higher results were obtained, however, by 
the modified Strowd method when nitrates were determined in different kinds of 
tobacco of variable nitrate content. 
4. The modified method was also found to be applicable for the estimation of 
nitrate in commercial fertilizers. No determinations were made by the regular 
Strowd procedure on these samples. 
5. The control determination which is necessary as a check in the modified 
procedure was found to be as accurate for the determination of ammoniacal 
nitrogen in fertilizers as the official magnesium oxid method. 
6. If both ammonia and nitrate are to be determined from aliquots of the 
same aqueous extract of a sample, it is necessary to filter from the residue. 
Where nitrate alone was determined in the samples used in this work, previous 
filtration proved to be of small advantage. 
7. The modified Strowd method is not recommended for general application 
for nitrate determinations until its reliability is established, but it is believed that 
its use can be extended to others of a different nature from those employed in 
this investigation. 
LITERATURE CITED 
(1) Association of Official Agricultural Chemists. 
1920. official and tentative methods of analysis. As compiled 
by the Committee on Revision of Methods. Revised to Nov. 
1, 1919. 417 p., illus. Washington, D. C. 
(2) Caron, H. 
1912. dosage des nitrates dans l’urine. Ann Chim. Analyt. 9: 
9-13. 
