198 Report OF THE CHEMIST OF THE 
is cut into small pieces with a spatula and stirred within the 
bottle, in order to mix the whole into as homogeneous a mass 
as possible. 
2. DEYERMINATION OF TOTAL NITROGEN IN CHEESE. 
We weigh out 1 or 2 grams of the cheese, prepared as de- 
scribed above, for the determination of the total nitrogen and 
treat it according to the Kjeldahl-Gunning method, modified as 
follows: When the solution has become partially digested, we 
add a piece of copper sulphate about as large as an ordinary 
pea. Unless this is done, it will take a long time to convert 
the organic nitrogen completely into ammonia. 
3. EXTRACTION OF WATER-SOLUBLE PRODUCTS. 
In a porcelain mortar we thoroughly mix 25 grams of our 
cheese sample, prepared as indicated above, with about an 
equal bulk of clean quartz sand. This mixture is transferred 
to a 450 cc. Erlenmeyer flask, to which we add about 100 cc. 
of distilled water at a temperature of 50° C. The flask is then 
placed on a water bath or in some place where it can be kept 
at a temperature of 122° F. to 131° F. (50° C. to 55° C.), and is 
allowed to stand for half an hour, being vigorously shaken from 
time to time. The liquid portion is then decanted through a 
filter of absorbent cotton into a 500 ce. flask. The residue is 
again treated with 100 cc. of water, heated, agitated, and the 
liquid decanted as before. This process is repeated, until the 
filtrate after being cooled to room temperature, amounts to 
500 ce., exclusive of the fat, which usually is present at the 
top of the liquid. 
The cotton filter mentioned is made of two layers of absorb- 
ent cotton prepared as follows: In a glass funnel we place 
some absorbent cotton to the depth of about one inch, moisten 
this with water, in order to compact it, and then above this 
place another layer of cotton of the same thickness. Upou 
this we pour our portions of cheese extract. This kind of 
filter allows rapid filtration without the aid of a pump, and 
is as effective in every way as paper, which requires half a day 
