centimeters of an infusion, made by shaking for ten minutes 200 grams 
of fresh soil, taken from the citrus orchard of this station, with 250 
cubic centimeters of sterile water was then added to each beaker and 
thoroughly mixed with the contents. The beakers were covered with 
watch glasses and the mixtures incubated at 28° C. The ammonia 
was determined at intervals, as shown in the table, by three different 
methods. One portion was distilled directly with magnesia; three 
other portions were first shaken with 250 cubic centimeters of 1 per 
cent hydrochloric acid, allowed to stand for an hour, and then filtered. 
An aliquot of one of these, corresponding to 75 per cent of the mate- 
rial used, was made alkaline with magnesia and distilled, while 
aliquots of the other two portions were distilled with caustic soda. 
The results obtained were as follows: 
Amount of ammonia formed in silica sand from different substances. 
Method of determination. 
Nitrogen as ammonia from— 
Period of incu- 
bation. 
Casein. 
Dried 
blood. 
Soy bean 
cake 
meal. 
Cotton- 
seed 
meal. 
Linseed 
meal. 
[Distilled directly with MgO 
iHCl solution distilled with MgO . . 
JHC1 solution distilled with NaOH . 
(Distilled directly with MgO 
1 HC1 solution distilled with MgO . . 
[HCl solution distilled with NaOH . 
[Distilled directly with MgO 
1 HCl solution distilled with MgO . . 
[HCl solution distilled with NaOH . 
/HCl solution distilled with MgO . . 
\HC1 solution distilled with NaOH . 
Mg. 
49.0 
47.2 
/ 44.4 
\ 42.0 
52.1 
44.8 
/ 44.8 
\ 41.2 
Lost 
41.1 
/ 35.5 
\ 34.4 
25.2 
24.8 
Mg. 
4.5 
2.8 
4.2 
4.2 
14.3 
15.0 
15.9 
15.0 
26.0 
24.9 
Lost 
29.1 
19.8 
23.5 
Mg. 
13.4 
12.0 
9.9 
10.3 
27.9 
20.5 
22.4 
22.6 
21.7 
20.4 
20.2 
20.2 
13.0 
19.6 
Mg. 
6.2 
4.8 
4.3 
4.1 
12.7 
12.3 
12.5 
11.6 
12.9 
10.4 
10.4 
12.3 
11.2 
9.9 
Mg. 
7.3 
5.6 
6.4 
5.6 
16.2 
13.1 
6 days 
14.9 
14.7 
17.9 
14.2 
9 days 
15.9 
16.8 
14.9 
14.7 
The different materials were converted into ammonia at greatly 
different rates. Casein was the most readily ammonified, the con- 
centration of ammonia having reached a maximum at the end of 
two days, when about 40 per cent of the nitrogen had been converted 
into ammonia. After four days the ammonia content became con- 
siderably reduced. In view of the yields of ammonia found in experi- 
ments with soil (Series II) it is probable that ammonification was 
active for longer than two days, but then evaporation and nitrifica- 
tion more than equaled ammonification. The rapidity with which 
casein 1 was ammonified as compared with the other materials is 
especially interesting. 
The formation of ammonia from dried blood took place slowly 
during the first two days, but later the yield approached that from 
casein. Soy bean cake meal was ammonified considerably more 
i See Brown, Iowa Sta. Research Bui. 11; Centbl. Bak„. [etc.], 2. Abt., 39 (1913), pp. 61-73. 
96280°— 15 2 
