32 
Sm J. B. LAWES AND PROFESSOR J. H. GILBERT ON THE 
Turning now to the parallel results obtained with the lucerne surface soil, which, 
though poor, still contained about twice and a half as much nitrogen as the subsoil, it 
is seen that much more nitrogen was found in the extracts than in those from the 
subsoil. At the same time the liquids after contact showed scarcely a trace of acidity, 
and they were found to contain much more of other dissolved matters. In the first 
extraction, after 1 hour 9‘7 2, and after 24 hours 8’51 parts of nitrogen were taken up 
per million of soil; and in the second extraction 6'08 and 7'59 parts per million. 
That there was less nitrogen taken up by the second quantity of acid than by the first, 
is doubtless due to the more readily soluble portion having been already removed. 
Even in the second extraction of this richer, though still poor, surface soil, about 
three times as much nitrogen was taken up as from the subsoil. 
In the experiments so far considered, nearly the whole of the acid was neutralised 
in the first extraction of the subsoil, and in both extractions of the surface soil. In 
the experiments, the results of which are recorded in the lower division of the table, 
only half the quantity of subsod or surface soil was mixed with 1000 c.c. of the acid 
solution; and here, in the case of the subsoil the liquids remained distinctly acid in 
the first extraction, even after 24 hours’ contact, and more strongly acid in the second 
extraction. In the case of the surface soil, however, in the first extraction the 
acidity was entirely neutralised, and even in the second extraction nearly so. 
The figures show that considerably more nitrogen was taken up, even from the 
subsoil, when twice the quantity of acid solution was used to a given quantity of it, 
and when, accordingly, the extracts remained more or less strongly acid. In the first 
extraction the quantities of nitrogen found in solution were, after 1 hour 3'2 8, and 
after 24 hours 7'29, per million soil; that is the more the longer the contact when the 
liquid remained distinctly acid. In the second extraction, with still greater remaining 
acidity, the amounts were 4'03 after 1 hour, and only 3'61 after 24 hours. That 
notwithstanding there was much more remaining acidity, there should be less taken 
up after 24 hours in the second than in the first extraction, again indicates that a 
certain quantity of the nitrogen exists in a more readily attackable condition than the 
remainder. It may be added, that much more mineral matter as well as nitrogen was 
taken up with the larger proportion of acid solution to a given weight of the subsoil. 
With the larger quantity of acid solution to a given weight of the surface soil, 
much more nitrogen was taken up than under parallel conditions with the subsoil. 
But, in the first extraction there was little more, and in the second even less, than 
with twice the quantity of the surface soil to a given quantity of the acid solution. 
In fact, there was, taking the two extractions together, even less nitrogen taken up 
with the larger than with the smaller proportion of acid solution to a given weight of 
soil; but with the larger proportion there was much more mineral matter taken up, 
whereby the acid would be to a greater degree neutralised. There is, both after 
1 hour and after 24 hours, much less nitrogen taken up in the second than in the first 
