10 
considerably higher percentage of the nitrogen of soils than are 
reported to occur in vegetable proteins. For example, the investiga- 
tions of Osborne show that, on an average, the seed proteins con- 
tained 11.6 per cent of their nitrogen as amids. In a few cases, 
however, as, for example, gliadin from wheat and rye and hordein 
from barley, the amids comprised more than 20 per cent of the total 
nitrogen. On the other hand, a large number of proteins studied 
were found to contain considerably less than 10 per cent of their 
nitrogen in amid form. 
A direct comparison of the amid nitrogen of the above soils with 
that found in soils elsewhere is possible in a few cases only, for the 
reason that the strengths of the acid, and the lengths of the time of 
digestion, used in the investigations on this subject vary so greatly. 
With the results obtained by Jodidi, however, our data are compar- 
able, and from his work on Michigan peat and Iowa soils the amounts 
of amid nitrogen found were approximately the same as those found 
in Hawaiian soils. 
BASIC NITROGEN. 
The percentage of nitrogen precipitated by phosphotungstic acid 
was found to vary considerably in the different soils studied, but 
on the average to be similar to the amounts reported by Jodidi. In 
these studies no attempt was made to prove the nature of these nitrogen 
compounds, but from the work of others it seems permissible to 
consider them as being composed principally of diamino acids. It is 
noteworthy that the percentages of basic nitrogen' in soils fall far 
below the percentages found in the majority of vegetable proteins. 
With the exception of glutenin from wheat, gliadin from wheat and 
rye, hordein from barley, and zein from maize, the basic nitrogen 
comprises more than 20 per cent of the total nitrogen in the vegetable 
proteins previously studied, and in a number of instances even more 
than 30 per cent of it. The basic nitrogen compounds of Hawaiian 
soils comprise only about 10 per cent of the total nitrogen. 
Since the principal diamino acids that occur in vegetable proteins 
are arginin, histidin, and lysin, each of which can be precipitated 
from dilute solutions by phosphotungstic acid, it may be assumed 
that these compounds contain the principal diamino nitrogen split 
off in the hydrolysis of soil organic matter. The amounts found 
vary considerably. This may be accounted for in part by the fact 
that the phosphotungstic acid method, in order to give reliable results, 
must be conducted under as definite conditions as possible. In view 
of the presence in the solution of various inorganic salts dissolved in 
the hydrochloric acid digestion, it is hardly to be supposed that the 
conditions of this precipitate were indentical with the different soils. 
The precipitate is slightly soluble in the solutions employed, and 
