22 
(6) The solubility in 3 per cent sodium hydrate varied from 49.56 
per cent to 76.62 per cent of the total nitrogen. Of the nitrogen thus 
dissolved, 57.85 per cent was precipitated by dilute hydrochloric acid, 
of which 11.93 per cent (expressed in percentage of the humus nitro- 
gen) remained insoluble after boiling in strong hydrochloric acid for 
10 hours. Amids comprised 28.77 per cent of the humus nitrogen, of 
which about one-half existed as amid in the original humus solutions, 
, and which remained in solution upon acidifying with hydrochloric acid. 
The remaining half was split off when the humus, precipitated by 
hydrochloric acid, was subjected to acid hydrolysis. The basic nitro- 
gen ranged from 4.39 per cent to 44.83 per cent of the humus nitrogen, 
increasing as the total nitrogen of the humus decreased. Nonbasic 
nitrogen was found to constitute 53.38 per cent of the humus nitrogen, 
of which 25.05 per cent existed as such in the original humus solutions. 
(7) The amounts of amid and basic nitrogen in humus expressed as 
percentages of the humus nitrogen were found to be higher than the 
amounts obtained by subjecting the original soil to hydrolysis. 
(8) In view of the large amounts of amid occurring in humus solu- 
tions, it was found better to use sodium hydrate as the solvent for 
extracting humus that is to be used for total humus nitrogen deter- 
minations. 
(9) The humus of Hawaiian soils contains a small percentage of 
nitrogen (5.88 per cent as an average of 22 samples), in which respect 
the humus of these soils closely resembles that found in humid soils 
in the States. 
o 
