54 2 
Journal of Agricultural Research voi. xxvi. no. h 
The acidity of the coffees made by these various methods, using brom- 
thymol blue as indicator, is shown in the following table: 
Table I .—Acidity of co ffee made by various methods 
Method. 
N/ioNaOH re¬ 
quired to neu¬ 
tralize 100 cc. 
of coffee. 
Hydrogeivion 
concentration. 
Boiled. 
Cc. 
11. O 
H-5 
12. 0 
Ph 
4. 92 
4. 9 1 
4. 92 
Percolated. 
French drip. 
There was practically no difference in the acidity of the coffee made 
by these methods. Because of this fact it was considered unnecessary 
to run cream tests on coffee made by all three methods. The French 
drip method was selected for all the experiments. Fifty grams of 
pulverized coffee were used to 1,000 cc. of water. 
GRADE OF COFFEE 
Three different grades of coffee of known quality—high, medium, and 
low—were obtained through the New York office of the Bureau of Chem¬ 
istry. These three grades and a special brand of coffee purchased on the 
market were used in experiments on the effect of different grades of cof¬ 
fee on feathering. 
The titratable acidity of the different grades, using brom-thymol blue 
as indicator, was practically the same for all and was as follows: 
Table II. — Acidity of coffee of different grades 
Grade. 
N/20 NaOH 
required to 
neutralize 100 
cc. of coffee. 
High. 
Medium. . . . 
Low. 
Special brand 
i 
i 
I 
12.0 
12 .a 
12.s 
12.5 
There was no noticeable difference in the effect of these various grades 
of coffee on the feathering of the cream, as shown in a total of 120 tests 
run on each coffee, in which the following grades of cream were used: 
Raw cream testing 20 per cent butterfat, pasteurized cream testing 20 per 
cent, pasteurized and homogenized cream testing 20 per cent, and raw 
cream testing 35 per cent. 
method of mixing cream and coffee 
In the remaining experiments the special brand of coffee was used. 
The average temperature of the coffee at the actual time of mixing the 
cream with it was about 95 0 C. Each experiment consisted of— 
