340 
Journal of Agricultural Research 
Voi. xxvm, No. i 
Ether extract. —The residue remaining from the moisture determination was 
pulverized and extracted with absolute ether in a Soxhlet apparatus. The ex¬ 
tracted material was weighed directly in the extraction flask after the ether had 
been driven off and the residue had been brought to constant weight at 100° C. 
Total nitrogen. —Total nitrogen was determined by the Kjeldahl-Gunning 
method. 
Purin nitrogen. —Purin nitrogen was determined by the method of Kruger and 
Schittenhelm ( 9) as modified by Fellenberg (8 ). 
Glycogen. —Glycogen was determined by the method of Pfliiger as described 
by Grube (5). 
Dextrose. —Dextrose was determined by the method of Hoagland ( 6). 
Preparation of cold-water extract. —The cold-water extracts were prepared by 
macerating 50 grams of sample with a convenient amount of water, and washing 
the mixture into a volumetric flask with sufficient water to bring the final volume 
to 1,000 cc. The suspension thus obtained was shaken about eight times in the 
course of 24 hours and filtered through a dry, folded filter. The water employed 
in preparing the extract was cooled before used to a temperature of 2° C., and 
the operations described were conducted in a cold-storage room maintained at 
the same temperature. The filtered extract served for the determination of 
total creatinin and of inorganic phosphorus. 
Total creatinin. —Total creatinin was determined in 200 cc. of the cold-water 
extract by the Folin method (4). 
Inorganic phosphorus. —Inorganic phosphorus was determined in 200 cc. of 
the cold-water extract by the method of Chapin and Powick (2), “Modification 
B” of this method being employed. 
Total phosphorus. —Total phosphorus was determined essentially by an adapta¬ 
tion of the Lorenz (10) method. When other ash constituents were not deter¬ 
mined, the procedure was identical with that which has been described elsewhere 
(8) in connection with the analysis of muscular tissue. When a more or less 
complete ash analysis was made, an aliquot of the solution obtained from the 
wet combustion of a much larger sample was employed for this determination. 
Preparation of solution for determination of ash constituents. —For the determi¬ 
nation of the ash constituents, 100 grams of the prepared sample were digested 
with a nitric-sulphuric acid mixture in a Kjeldahl flask, care being taken to employ 
minimal quantities of sulphuric acid. As a rule a satisfactory combustion could 
be obtained by employing about 150 cc. of fuming nitric acid, added in small 
portions, and 10 cc. of concentrated sulphuric acid. After complete destruction 
of the organic matter, the clear solution was diluted to a volume of 250 cc. in a 
volumetric flask, and a 10 cc. aliquot was removed for the determination of total 
phosphorus by the method indicated. The main portion of the solution, together 
with washings from the pipette, was transferred to a 400 cc. beaker and evapo¬ 
rated, the residue being heated cautiously until the free sulphuric acid had been 
volatilized. The material was then dissolved in 5 cc. of concentrated hydrochloric 
acid and diluted with water to a volume of 100 cc. (Solution A.) 
Copper. —When copper was determined, Solution A was heated to incipient 
boiling and saturated with hydrogen sulphid in an Erlenmeyer flask, which was 
then stoppered and allowed to stand over night. The copper sulphid was then 
filtered off, washed with hydrogen-sulphid water, and used for the determination 
of copper by Lowe's iodometric method ( 1 , p. 79). 
Separation of metals and alkaline earths from alkalies. —The filtrate from the 
copper sulphid was boiled to expel hydrogen sulphid and was treated with a little 
nitric acid to insure the oxidation of iron to the ferric condition; or when copper 
was not determined Solution A was treated directly with nitric acid. The solu¬ 
tion, which always contained a large excess of phosphoric acid, was then made 
