THE NITROGEN OF PROCESSED FERTILIZERS. 
was found to be that magnesia under such conditions changes a part 
of the amino nitrogen of cystine into ammonia. In this laboratory 
it was also found that by boiling cystine with lead oxide one of the 
amino nitrogen groups of this compound was split off almost quanti- 
tatively, ^vith the concurrent splitting off of hydrogen sulphide. 
Furthermore, it has been shown that if the amide nitrogen from 
protein l:ydrolysis is determined by distillation with a weak alkali, 
such as calcium hydroxide, at a temperature not to exceed 40° to 
42° C. in the bath and at a pressure of from 10 to 12 millimeters, 
no decomposition of cystine takes place. ^ 
In the manufacture of base goods the hair which is used contains 
proteins which on acid hydrolysis yield a high percentage of cystine. 
This fact, together with the analytical results just discussed, suggest 
rather strongly that there is present in the base goods more or less 
cystuie, although this evidence can not be considered conclusive, 
since it is possible that in such a heterogeneous mixture there may 
be present other nitrogenous compounds which would be decomposed 
by magnesia or litharge with the liberation of ammonia. 
NITROGEN PARTITION. 
For the purpose of determining the different forms of nitrogen 
present in the base goods the method of Van Slyke ^ was followed 
m its essential details, except that the determination of cystine, 
was not made. The method for the determination of this compound, 
accordmg to the procedure used by Van Slyke, depends not upon a 
nitrogen determination but upon the determination of the amount 
of sulphur in the compounds precipitated by phosphotungstic acid. 
This determination when made on the hydrolytic products of acid 
digestion of pure protein, may give quite satisfactory results, but the 
raw materials from which base goods are made contain many organic 
compounds other than proteuis or protein decomposition products, 
and this is of course particularly true in the case of garbage tankage. 
It is well kno^vn that niany plant and animal substances contain 
sulphur in a variety of linkages, and garbage tankage no doubt con- 
tains sulphur in other forms than that of cystine. The hair and 
leather used have both undergone some decomposition before the 
acid treatment and it is not impossible that the cystine originally 
present m the proteuis may have been changed into sulphur com- 
pounds of a different chemical nature. No doubt some sulphur com- 
pounds other than cystine are precipitated by phosphotungstic acid, 
so that a determination of cystine depending on the sulphur content 
of the phosphotungstic acid precipitate would be of uncertain value 
in dealing with material of unknown origin and of such a hetero- 
geneous character as fertihzer goods. 
1 Gumbel, nofmeister's Beltrage, .5, 207 (1904). 2 j. Biol. Chem., 10, 1.5-5.5 (1911). 
