8 BULLETIN 158, U. S. DEPARTMENT OF AGEICULTUEE. 
Van Slyke has shown that certain corrections must be appUed in the 
method, owing to the fact that the phosphotimgstates of the dianiino 
acids are slightly soluble, and these corrections have been applied 
just as though the fractions contained only the hydrolysis products 
of pure proteins. In Table V the combined results of the analyses are 
given. 
The above analytical procedin-e which separates the nitrogen into 
different groups, gives results than can only bo rigidly interpreted 
when the products of the acid hydrolysis are known. The results of 
the analj^sis cf base goods by this method can only be clsarly imder- 
stood when further facts regarding the compounds, in which tha 
nitrogen is contained, are discovered. A description of the methods 
used in isolating and identifying certain of these compounds follows. 
ISOLATION AND IDENTIFICATION OF DEFINITE COMPOUNDS FROM 
THE PROCESSED FERTILIZER. 
Ten pounds of base goods were extracted by boiling for 1 hour with 
20 gallons of water in a steam- jacketed kettle. The solution was 
filtered from the insoluble residue, made exactly neutral with caustic 
soda, the precipitate formed filtered off, and the filtrate concentrated 
in a steam kettle to a volume of about 3,500 c. c. 
This solution contained phosphates, sulphates, and much other 
mineral matter. In order to separate as much of these salts as pos- 
sible from the organic compounds a cold saturated solution of barium 
hydroxide was added to the solution until no further precipitation 
took place. The heavy precipitate which formed was filtered off by 
suction and washed many times with water. The fxltrate was exactly 
neutralized with sulphuric acid and concentrated to a volum.e of about 
2,000 c. c. After cooling, this solution was m^ade acid to 5 per cent 
with sulphuric acid and a solution of phosphotungstic acid was added 
to shght excess, and the mixture allowed to stand. 
After 3 days the precipitate which formed was filtered off and 
washed with water containing about 5 per cent sulphuric acid and a 
little phosphotungstic acid. The precipitate was carefully dissolved 
in 45 per cent caustic-soda solution, using phenolphthalein as an indi- 
cator and adding at no time more than two drops of the alkali solution. 
Water was added sq that a volumo of about 1,500 c. c. was reached, 
and barium hydroxide solution was added until the phosphotungstic 
acid was precipitated. After filtering off the barium phosphotung- 
statO; the free alkaU was just neutralized with sulphuric acid, and the 
solution was then evaporated almost to dryness with barium carbonate 
in order to e:^el all of the ammonia. The residue was taken up in 
about 1,000 c. c. of hot water and filtered, and the precipitate washed 
with hot water. The filtrate was placed in a 5-liter flask and treated 
while hot with solid silver sulphate, which was added slowly until the 
