24 The Colorado Experiment Station 
cation of the spots relative to the surrounding surface nor the con¬ 
dition of the vegetation was given. The clumps of one of the 
samples showed distinctly a thin, white incrustation on their upper 
surfaces. The sample was quite sandy and judging from the 
clumps of soil had been taken to a depth of from one to two inches. 
The second sample was quite different in character and described 
by the sender as being always moist. 
The sample numbered one and described as white alkali soil 
contained 8.886 percent of water soluble salts. The nitric acid in 
this soluble portion corresponded to 3.939 percent of sodic nitrate 
or 0.350 percent of sodic nitrate calculated on the air dried soil. 
This corresponds to 2,333 pounds of sodic nitre in the surface two 
inches of soil per acre. I do not know anything about the size or 
location of the areas represented, nor do I know the condition of the 
vegetation in or about the places where the samples were collected. 
One of the samples was a sandy soil and was very probably 
taken to only a very shallow depth. The sender says that it was 
scraped up.- I would judge from the thickness of the clumps in the 
sample that from one to two inches of the surface soil had been 
taken. 
We find the nitrates present in soils, where there is a great 
deal of moisture, but in places where there is too much water, the 
nitre does not appear. In little valleys and saucer shaped depres¬ 
sions in which the lower portions are too wet there is no visible 
alkali, then follows a zone where white alkali abounds and above 
this the nitre is formed. I do not mean to say that there may not 
be nitre mixed with the white alkali but that the nitre in such 
cases appears in higher ground than that on which the white alkali 
usually appears. Furthermore, it is not intended that anyone shall 
infer that it is only in valleys and depressions that the nitre occurs. 
Two instances of the occurrence of nitre suggest themselves, one 
of which is on the side of a hill, and the other on a little reach of 
rising land at the foot of a hill. It is at least 10 feet higher than 
land 200 yards away, in short, it is on the gently sloping portion 
of a hill. These two instances are very far removed from any 
other occurrences so far mentioned and are nearly 300 miles apart. 
These occurrences are furthermore very rich in nitrates. 
The next sample is an alkali collected from the face of a shale 
bank from which issued the seep or drainage from an irrigated 
mesa. The water issuing from this bank contained 176.96 grains 
total solids per imperial gallon, ignition 21.42 grains. There are 
no carbonates present. The efflorescent alkalis on this shale bank 
were white and consisted essentially of magnesic and sodic sul¬ 
fates, but carried about 2.3 per cent nitrates. 
