microscopical slide.
Cover with cover glass and examine under the microscope.

In the evaporating dish cook a small piece of potato, then place a very
small portion upon the slide, and examine with the microscope.

Make drawings of the starch grains in raw and in cooked potatoes.

Experiment No. 7

Influence of Yeast on Starch Grains

Moisten a small portion of the dough prepared with yeast and with the
stirring rod place a drop of the starchy water upon the slide. Cover
with cover glass and examine under the microscope.

Repeat, examining a drop of starchy water washed from flour.

Make drawing of wheat starch grain in flour and in dough prepared with
yeast.

Experiment No. 8

Mechanical Composition of Potatoes

Wash one potato. Weigh, then peel, making the peeling as thin as
possible. Weigh the peeled potato and weigh the peeling or refuse.
Calculate the per cent of potato that is edible and the per cent that is
refuse.

Experiment No. 9

Pectose from Apples

Reduce a small peeled apple to a pulp. Squeeze the pulp through a clean
cloth into a beaker. Add 10 cc. H_{2}O and heat on a sand bath to
coagulate the albumin. Filter, adding a little hot water if necessary.
To the filtrate add 5 cc. alcohol. The precipitate is the pectose
material.

1. Is the pectose from the apple soluble? 2. Is it coagulated by heat?
3. Is it soluble in alcohol?

Experiment No. 10

Lemon Extract

To 5 cc. of the extract in a test tube add an equal volume of water. A
cloudy appearance indicates the presence of lemon oil. If the solution
remains clear after adding the water, the extract does not contain lemon
oil.

Why does the extract containing lemon oil become cloudy on adding water?

Experiment No. 11

Vanilla Extract

Pour into a test tube 5 cc. of the extract to be tested. Evaporate to
one third. Then add sufficient water to restore the original volume. If
a brown, flocculent precipitate is formed, the sample contains pure
vanilla extract. Resin is present in vanilla beans and is extracted in
the essence. The resin is readily soluble in 50 per cent alcohol. If
the alcohol is removed from the extract, the excess of resin is
precipitated, or if free from alkali, it may be precipitated by diluting
the original solution with twice its volume of water. Test the two
samples and compare.

(Adapted from Leach, "Food Inspection and Analysis.")

1. Describe the appearance of each sample after evaporating