446 F. H. Storer—Ferment-theory of Nitrification. 
the contents of No. 10. It appeared from these results that 
there had been formation either of a nitrate or nitrite in each 
of the bottles which contained humus, and no such formation 
in either of the other bottles; but the thought suggested itself, 
that the small amount of nitrogen oxides found in No. 7 may 
perhaps have been dragged over mechanically from No. 8 by 
the current of air. 
A second series of tests was made upon Nos. 8, 9 and 10, 
to see which of them gave the weakest reaction, 25 ce. of liquid 
being taken from each bottle and diluted with pure water to 
the volume of 100 cc. before applying the test. It appeared 
again that No. 10 gave the strongest reaction and that No. 8 
gave the weakest. Roughly estimated, the strength of the 
reactions from jars Nos. 10, 9 and 8 were to one another as 
It may here be said that humus was employed in these exper- 
iments for the sake of testing the old observation of Millon,* 
who noticed that ammonium salts are changed to nitrates when 
in contact with oxidizing humus, and who argued that the 
chemical action originated by the coming together of humus 
and oxygen, was communicated to the ammonium compound. 
In his own words: “The oxidation of the humic acid is the 
cause of the oxidation of the ammonia.” 
e 
chloride; No. 14 pure water; No. 15 pure water, the same 
warming the laboratory. The current of air passed this time in 
the direction from No. 1 to No. 15; it was maintained constantly 
* Kopp and Will’s Jahresbericht der Chemie, 1860, xiii, 101 and 1864, xvii, 158. 
