358 Messrs Parvis and Gourtauld, Decomposition and nitrification 
alkaline solutions than in the non-alkaline solutions, and (3) a 
progressive diminution in the total ammonias. The larger figures 
for the free ammonia in the alkaline solutions may be owing to 
the influence of the soda ; and this corresponds to the results 
of Purvis and Coleman, who found that higher numbers were 
obtained in the artificial solutions of the salts incubated with 
sewage. It may be that the alkali breaks down the complex 
albuminoids with the production of free ammonia in larger 
quantities than in the non-alkaline solutions. Or, it may be 
caused by the more efficient action of certain organisms which 
notoriously carry on their work better in alkaline than in neutral 
solutions. Against the latter argument is the important fact that 
the nitrate figures are lower in the alkaline solutions, where there 
was a suitable base to fix the nitric acid as it was produced*. 
But, whatever be the explanation of these differences, the general 
results are comparable with the incubations with salt solutions 
Incubation 
Alkaline solution 
Free NH„ 
Albumin- 
oid nh 3 
Total NH 3 
Nitrates 
Nitrites 
Sample III . 
24 hours 
48 hours 
72 hours 
7 days 
37 clays 
49 days 
0-729 
0-608 
0-619 
0-640 
0-330 
0-480 
0-200 
0-160 
1-059 
1-088 
0-819 
0-800 
0-020 
0-012 
0-012 
absent 
trace 
0-021 
absent 
trace 
\ small 
/ trace 
) distinct 
/ trace 
Incubation 
Non-alkaline solution 
Free NH 3 
Albumin- 
oid NH 3 
Total NH 3 
Nitrates 
Nitrites 
Sample III . 
24 hours 
48 hours 
72 hours 
7 days 
37 days 
49 days 
0-890 
0-768 
0-860 
0-880 
0-320 
0-310 
0-310 
0-210 
1-210 
1-078 
1-170 
1-090 
0-020 
0-015 
0-011 
absent 
0-075 
absent 
33 
33 
33 
f distinct 
) trace 
Boulanger and Massol have shown that ammonia inhibits the development of 
nitric-acid-forming organisms, hut not their activity when once developed. Annul, 
ile Vlnstitut Pasteur , xvn. and xvm. 
