32 
Bulletin 65. 
DISCUSSION OF ANALYSIS. 
§ 67. This analysis shows that 65 per cent, of the potash, 63 
per cent, of the alumina, 90 per cent, of the oxid of iron, 27.6 per 
cent of the silicic acid, a very high percentage of the lime and mag¬ 
nesia, and the whole of the sulfuric and phosphoric acids, were 
removed or, as in the case of the silicic acid, rendered soluble in 
sodic carbonate. If the silicic acid rendered soluble by this treat¬ 
ment be taken as the measure, then the action of the hydrochloric 
acid on the soil was between six and seven times as great as it was 
on pure feldspar, and probably not more than one sixth of the 
silicic acid could come from the decomposition of this mineral. 
The potash dissolved out of the soil is about 75 per cent, greater 
than was taken into solution from the pure, fresh mineral. The 
relative amount of soda dissolved out of the feldspar was high com¬ 
pared with the amount of potash dissolved, but low when compared 
with the percentage of soda dissolved out of the soil. A glance 
at the analysis shows that, taken roughly, 50 per cent, of the soda 
in the soil was dissolved out, but only about 25 per cent, of it went 
into solution in the case of the feldspar. The relatively large 
amount of soda dissolved out of the feldspar by digestion with the 
dilute hydrochloric acid, is probably due to the fact that the feld¬ 
spar used was not wholly composed of the potash feldspar, ortho- 
clase, but may have contained an admixture of oligoclase, another 
feldspar, rich in soda and more readily attacked by acids. When 
we take up the portion of the soil soluble in water we shall see that 
some, as much perhaps as one third, of the soda is present in a form 
readily soluble in this menstruum, and in this case belongs to the 
u alkalis ” present. 
THE WATER SOLUBLE IN THE SOIL. 
§ 68. When these soils are treated with fresh portions of water, 
so long as they yield either chlorin or sulfuric acid to the water and 
the amount taken into solution is determined, we find it ranging 
from 0.389 per cent, to 2.550 per cent. Soil A yielded the highest 
amount to water, 2.55 per cent., taking the sample to a depth of ten 
inches, and as high as 3.93 per cent, taking the first two inches of 
the soil. 
§ 69. In stating the analyses of the portions of different sam¬ 
ples soluble in water, I have combined the acids and bases and give 
the salts alongside of the direct analytical results. The order fol¬ 
lowed in combining them will be apparent to anyone upon an 
inspection of an analysis. I have adopted this order and have been 
as uniform as possible throughout. This order is convenient and 
probably represents the salts present in the soil as nearly as any 
other which might have been adopted, but it is certainly not always 
correct. 
