THE AMMONIA OF THE SOIL. 249 
‘The fact that caustic potash, a more energetic decom- 
posing agent than lime, disengaged more ammonia than 
the latter from the yellow clay, strengthens the view that 
ammonia is produced and not merely driven off under the 
conditions of these experiments, and that accordingly the 
figures are too high. Other chemists employing the same 
method have obtained similar results. 
Boussingault (Agronomie, T. IIT, p. 206) was the first 
to substitute magnesia for potash and lime in the estima- 
tion of ammonia, having first demonstrated that this sub- 
stance, so feebly alkaline, does not perceptibly decompose 
gelatine, albumin, or asparagine, all of which bodies, espe- 
cially the latter, give ammonia when boiled with milk of 
lime or solutions of potash. The results of Boussingault 
here follow. 
Localities. Quantity of Ammonia per cent. 
Liebfrauenberg, Alsatia 
Bischwiller, te 
Merckwiller, ap 
Bechelbronn, 5S 
Mittelhausbergen,, es 
Ile Napoleon, Mulhouse, 
Argentan, Orne, 
Quesnoy-sur-Deule, Nord, 
Rio Madeira, America, 
Rio Trombetto, # 
Rio Negro, se 
Santarem, se 
Tle du Salut, ee 
Martinique, se 
Rio Cupari, (leaf mold,) ‘' 
Peat, Paris, 
The above results on French soils correspond with those 
obtained more recently on soils of Saxony by Knop and 
Wolff, who have devised an ingenious method of estimat- 
ing ammonia, which is founded on altogether a different 
principle. ‘Knop and Wolff measure the nitrogen gas 
which is set free by the action of chloride of soda (Ja- 
velle water*) in a specially constructed apparatus, the 
* More properly hypochlorite of soda, which is used in mixture with bromine 
and caustic soda. 
11* 
