39

Examination of Tea Leaves

Soak a small amount of tea and unroll 8 or 10 of the leaves. Make a
drawing of a tea leaf. Observe the proportion of stems in each of three
samples of tea; also the relative proportion of large and small leaves.
Observe if the leaves are even as to size and of a uniform color.

Experiment No. 40

Action of Iron Compounds upon Tannic Acid

Make an infusion of tea by placing 3 gms. of tea in 100 cc. of hot water
and stirring well. Filter off some of the infusion and test 5 cc. with
ferrous sulphate solution made by dissolving 1 gm. FeSO_{4} in 10 cc.
H_{2}O and filtering. Note the result.

1. What change in color did you observe when the ferrous sulphate
solution was added to the tea infusion? 2. What effect would waters
containing iron have upon the tea infusion?

Experiment No. 41

Identification of Coffee Berries

Examine Rio, Java, and Mocha coffee berries. Describe each. Note the
characteristics of each kind of coffee berry.

Experiment No. 42

Detecting Chicory in Coffee

Fill a beaker with water and place about a teaspoonful of ground coffee
on the surface. If much of the ground material sinks and it imparts a
dark brown color to the lower portion of the liquid, it is an indication
of the presence of chicory. Pure coffee floats on water. Chicory has a
higher specific gravity than coffee.

1. How may the presence of chicory in ground coffee be detected? 2. Why
does coffee float on the water while chicory sinks? 3. What effect does
chicory have upon the color of water?

Experiment No. 43

Testing Hard and Soft Waters

Partially fill a large cylinder with very hard water. This may be
prepared by dissolving 0.1 to 0.2 gm. calcium chloride in 500 cc. of
ordinary water. Add to this a measured quantity of soap solution. Mix
well and notice how many cubic centimeters of soap solution must be used
before a permanent lather is formed, also notice the precipitate of
"lime soap." Repeat this experiment, using either rain or distilled
water, and compare the cubic centimeters of soap solution used with that
in former test. Repeat the test, using tap water.

Soap Solution.--Scrape 10 gms. of castile soap into fine shavings and
dissolve in a liter of alcohol, dilute with 1/3 water. Filter if not
clear and keep in a tightly stoppered bottle.

1. Why is more soap required to form a lather with hard water than with
soft water? 2. What is meant by "lime soap"? Describe its