Fixation ot Nitrogen in Colorado Soils 
13 
extracts is not an accident confined to the two localities given, 
but is characteristic of this whole section. They will at least 
serve for comparison. 
These analyses have not been published heretofore. The 
alkali chosen was gathered from the low lands along the Poudre 
River, nearly opposite the point where the Box Elder Creek 
joins the river. 
WHITE AlilvALT. POUDRE RIVER ROTTOM LAND 
Percent 
Calcic sulfate ^ 7.935 
IMagnesic sulfate 46.353 
Sodic sulfate 41.926 
Sodij chlorid 1.894 
Sodic carbonate 0.756 
Potassic carbonate ' 0.5 65 
Sodic silicate ■ 0.364 
Ferric & Aluminic oxids • 0.098 
Manganic oxid (br) 0.109 
100.000 
This white alkali represents an efflorescence that at times 
appears very abundantly on some of these bottom lands. The 
soils, analyses of whose water-soluble por-tion are given above, 
usually show no efflorescences, which is a marked difference. 
The process of efflorescing is one whereby the less soluble, 
easily crystallizable, salts are separated from the more soluble 
and less easily crystallizing ones. This accounts in a large 
degree for the differences in the analyses given. But the or 
dinary alkalis do not appear on these soils as efflorescenses 
nor in the analyses of the water-soluble. If the white alkalis 
were present in these soils they would form efflorescenses under 
favorable conditions. This is a fact that can be observed at 
some places. 
The following is an effloresced, ordinary white alkali, col- 
lected from the margin of a very bad piece of ground in the 
Wellington District. The sample was scraped off the surface 
of the soil which was very wet at the timp the sample was taken. 
The surface was very uneven and I gathered a great deal of 
soil with the alkali. The water-soluble portion was 13.36 per- 
cent of the air-dried sample. Under these circumstances the 
separation of the salts by effiorescence was probably very much 
better than my separation of alkali and soil. The character of 
the effloresced salts, however, is not in the least obscured and 
they are clearly the usual mixture of sulfates constituting our 
ordinary alkalis, with a little nitrate from the soil. The com- 
position yas as follows : , 
