20 
Bulletin 65. 
course of the chemical changes which take place in the transforma¬ 
tion of a mass of rock fragments into true soil. The decomposable 
minerals, feldspar and mica, very subordinate in this case, are so 
acted upon that new minerals, having less silica but more alumina 
and possibly alkaline earths, are formed. The high percentage of 
lime in the analysis of the clay is almost certainly due to an ad¬ 
mixture of gypsum. It is scarcely possible, owing to the manner of 
preparation, that the higher percentage of magnesic oxid can be 
attributed to a similar cause. In regard to the potash, which is 
even higher in the dust than in the clay, though the experienced 
analyst will be inclined to consider them the same, there may be 
a question as to the manner in which it is present. This arises 
from the knowledge of facts obtained from other experiments and 
not from the analyse*. The testimony of the latter is, and it is in 
perfect harmony with what we know of the deportment of soil 
masses, that in the extremely small particles of the soil there is a 
tendency toward enrichment in potash. The indications of the 
analyses, contrary to the impressions of the writer, indicate that the 
maximum of this concentration is reached in the portion designated 
as dqSt, a portion whose individual particles have a diameter of 
less than 0.01 millimeter, or less than one twenty-five hundredths 
of an inch, and which constitutes 27.87 per cent, of this soil. The 
clay, which is still very much finer, contains, in this case, essentially 
the same percentage of potash, but constitutes only 8.31 per cent, of 
the soil. In this instance the dust and not the clay is the potash 
carrying silt-constituent of the soil. 
§ 40. The fine particles of the dust and clay are probably 
not wholly composed of fine residual parts of the minerals originally 
composing the soil mass, but are to a greater or less extent made up 
•of newly formed particles ol precipitates, or at least of newly formed 
minerals, which may adhere tenaciously to the fine residual grains 
•or form independent little aggregates which, being disintegrated by 
the washing of the soil, are obtained in the form of clay. 
ANALYSES OF PARTS OF FINE EARTH SHOW NO DEFINITE RATIOS. 
§ 41. Little can be said in regard to the ratios existing between 
the various chemical constituents as shown in the preceding 
analyses. There is, for instance, no clear and definite relation 
between the potash and soda, iron oxid and alumina, alkalies and 
alkaline earths. The iron is, taken roughly, equal to one half of 
the alumina. This holds true for soil A, the parts of the soil sepa¬ 
rated by washing, and of the Larimer county loess. I am inclined 
to think that this is an accident, in spite of its occurring in each of 
these six instances. It is not the case in the Chevenne loess, and 
extraction with hydrochloric acid shows it to be almost wholly 
soluble in this agent. Macroscopic observation, especially after 
