534 
Journal of Agricultural Research 
Vol. XXVIII, No 6 
This will be discussed later. Potassium nitrate was used and 0.25 gm. in solu¬ 
tion was added in each determination, including the control. 
When the filtered water extract of the sample was used the nitrate was added 
to this solution. Determinations were made on the whole sample and on the 
filtered aqueous extract of the same. In the latter aliquots were withdrawn 
from the same solution, one of which was used for the control. These are desig¬ 
nated in the table as “Filtered.” Those by the Ulsch-Street method were made 
in a similar manner and are likewise designated in the table. In all cases 0.7 
gm. of fertilizer or aliquots representing this amount were used. The initial 
volume for the distillation by the modified Strowd method was 350 cc. and 3 gm. 
of Devarda alloy, together with the Bunsen valve, was used. The results are 
given in Table V. 
Table V . —Comparison of the modified Strowd and Ulsch-Street methods for nitrate 
in fertilizers 
Number 
Modified Strowd 
method for recovery 
of added nitric N 
Ulsch-Street method 
for recovery of added 
nitric N 
Filtered 
Not 
filtered 
Filtered 
Not 
filtered 
63595_ _ 
Per cent 
98. 6 
97. 1 
Per cent 
95. 2 
99. 7 
Per cent 
Per cent 
93. 9 
Average 
97. 9 
97. 5 
63601 __ _ 
96. 0 
98. 8 
97. 7 
a 95. 1 
« 94. 2 
74. 0 
Average____ 
97. 4 
_ _ 
84. 1 
63605 _ _ _ 
98. 3 
97. 7 
95. 2 
96. 5 
92. 5 
Average _ _ 
98. 0 
95. 9 
63607 _ __ 
99. 7 
97. 4 
98. 8 
95. 7 
98. 6 
86. 7 
Average_ 
98. 6 
97.2 
63619 __ 
98. 6 
98. 6 
96. 2 
99. 7 
75. 7 
Average _ __ 
98. 6 
98. 0 
63621____ 
98. 0 
99. 1 
97. 1 
77. 2 
Average _ _ _ _ 
98. 1 
63899__ 
98. 0 
98. 3 
101. 7 
« 102. 9 
« 95. 7 
84. 5 
Average__ 
98. 2 
90. 1 
a Volume of solution was 350 cc. and collected 150 cc. of distillate. In the official method the prescribed 
volume is less than 150 cc. and only 100 cc. of distillate could be obtained. The solution of acid and iron 
was boiled for 10 minutes instead of 5 minutesjas recommended. 
