8 
The above data show that the soils of Hawaii are similar to soils 
elsewhere in that the nitrogen present as nitrate and ammonia consti- 
tutes but a small percentage of the total nitrogen. In contrast to 
ordinary soils the ammonia content in most instances was considerably 
greater than the nitrate. 1 The nitrogen of these soils exists, there- 
fore, very largely in organic combinations. 
ORGANIC NITROGEN. 
When a study is made of the organic nitrogen greater difficulties 
are at once encountered. The isolation of the various individual 
nitrogen compounds occurring in soils must necessarily be a tedious 
undertaking. It has been shown, however, that by means of the 
hydrolytic method as used in the study of protein chemistry, some 
conception can be obtained regarding the make-up of the nitrogen 
bodies of the soil. By the use of this method the amounts of nitrogen 
split off in the form of amids, diamino, and monamino acids are 
relatively easily determined. 
Partly on account of the readiness with which these determinations 
can be made, and partly for the reason that the soil nitrogen may 
reasonably be supposed to have originated largely from vegetable 
proteins, many of which are known to be susceptible to complete 
hydrolysis, use has been made of the process of hydrolysis in this 
work. In addition it seems probable that the action of bacteria on 
soil nitrogen is progressive and of a hydrolytic nature. 
On the other hand, the work of Osborne 2 and others show that 
the hydrolytic products vary widely with the different proteins and 
indicate that the results obtained in soil studies by the use of 
hydrolytic agents must be of the most general nature. Nevertheless, 
it is believed that much valuable information can be obtained in this 
way. 
In the work reported in this bulletin the Osborne-Harris 3 modifi- 
cation of the Hausmann 4 method, as outlined by Jodidi 5 in his 
studies on Iowa soils, has been used. The hydrolysis was conducted 
by heating to boiling under a reflux condenser for 10 hours 50-gram 
portions of the air-dried soils with 750 cubic centimeters strong hydro- 
chloric acid, filtering, and making the filtrate to 1 liter. Aliquots 
of the solution thus obtained were used for the determination of the 
amid, basic, and nonbasic nitrogen. The amid nitrogen, determined 
as ammonia by the direct distillation of the solutions after making 
alkaline with magnesium oxid, would also contain the ammonia orig- 
1 The occurrence of large quantities of ammonium compounds is a phenomenon common to many 
Hawaiian soils. 
2 The Vegetable Proteins. London and New York, 1909. 
8 Jour. Amer. Chem. Soc., 25 (1903), p. 323. 
'Ztschr. Physiol. Chem., 27 (1899), p. 95. 
» Iowa Sta. Research Bui. 1 (1911). 
