The Soil. 
43 
distillation with pure water, prove the presence of both ammonical 
salts and free ammonia in this soil, and the samples show that 
the amount of them was not dependent upon the manure added 
to the soil one year previous to the time that they were taken. 
I interpret the formation of ammonia salts and free ammonia in 
this soil, as indicating unfavorable biological conditions. The 
sample numbered 1 in 1 his series is from that section of the plot 
which I have described elsewhere as a paludal soil. Its reclama¬ 
tion was not at this time complete.' I may be mistaken in this 
view, but I believe it to be the explanation, and that the larger 
quantity of ammonical salts and free ammonia were due to the 
greater resistance this soil had presented to the ameliorating effects 
of cultivation. 
§ 86. The examinations made of the ground waters, not only 
strengthen but extend this view. The ground waters show not only 
ammonia, but large amounts of nitrites, indicating a probable re¬ 
duction of nitrates in some zone of the soil. The presence of am¬ 
monia in the upper portions of the soil is probably the most sus¬ 
picious of all of our facts, as it seems to indicate a slow oxidation, 
and brings the zone of denitrification to the very surface. 
VOLATILE ACIDS IN THE SOIL. 
§ 87. The conditions obtaining in this soil being such that 
acid fermentations might take place, an attempt was made to deter¬ 
mine the quantity of such acids, if any were present. Two samples 
of soils were examined for volatile acids; one had received manure 
and the other had not. The sample which had received manure 
yielded volatile acids, other than hydrochloric, equal to 1.3 c. c. of 
one hundredth normal soda solution. The one which had not re¬ 
ceived manure yielded volatile acids corresponding to 10.30 c. c. of 
the soda solution. These are exceedingly minute quantities and 
their only possible value is a qualitative one, suggesting that one of 
the effects of the manure added was to lessen the amount of these 
acids in the soil by modifying the character of the changes taking 
place within the soil. 
NITROGEN AND NITRATES IN THE SOIL. 
§ 88. Less has been done with this subject than appears de¬ 
sirable. My excuse is, that I have tried to study this subject in.con¬ 
nection with the ground water, rather than with the soil, because 
there is no material and permanent accumulation of the nitrates in 
the soil, where it receives water enough, either as rainfall or as irri¬ 
gation, to remove them more or less nearly at the same rate at 
which they are formed in the soil. 
§ 89. The samples in which the total nitrogen was determined 
are comparable in a general way only, owing to the fact that the 
