re remains
on the cloth a grayish white, sticky, elastic "gluten," made up of
albumen, some of the ash, and fats. Draw out some of the gluten into
threads, and observe its tenacious character.

Experiment 42. Shake up a little flour with ether in a test tube,
with a tight-fitting cork. Allow the mixture to stand for an hour, shaking
it from time to time. Filter off the ether, and place some of it on a
perfectly clean watch glass. Allow the ether to evaporate, when a greasy
stain will be left, thus showing the presence of fats in the flour.

Experiment 43. Secure a specimen of the various kinds of flour, and
meal, peas, beans, rice, tapioca, potato, etc. Boil a small quantity of
each in a test tube for some minutes. Put a bit of each thus cooked on a
white plate, and pour on it two or three drops of the tincture of iodine.
Note the various changes of color,--blue, greenish, orange, or yellowish.

Experiments with Milk.

Experiment 44. Use fresh cow's milk. Examine the naked-eye character
of the milk. Test its reaction with litmus paper. It is usually neutral or
slightly alkaline.

Experiment 45. Examine with the microscope a drop of milk, noting
numerous small, highly refractive oil globules floating in a fluid.

Experiment 46. Dilute one ounce of milk with ten times its volume of
water. Add cautiously dilute acetic acid until there is a copious,
granular-looking precipitate of the chief proteid of milk (caseinogen),
formerly regarded as a derived albumen. This action is hastened by
heating.

Experiment 47. Saturate milk with Epsom salts, or common salt. The
proteid and fat separate, rise to the surface, and leave a clear fluid
beneath.

Experiment 48. Place some milk in a basin; heat it to about 100 degrees
F., and add a few drops of acetic acid. The mass curdles and separates
into a solid curd (proteid and fat) and a clear fluid (the whey), which
contains the lactose.

Experiment 49. Take one or two teaspoonfuls of fresh milk in a test
tube; heat it, and add a small quantity of extract of rennet. Note that
the whole mass curdles in a few minutes, so that the tube can be inverted
without the curd falling out. Soon the curd shrinks, and squeezes out a
clear, slightly yellowish fluid, the whey.

Experiment 50. Boil the milk as before, and allow it to cool; then
add rennet. No coagulation will probably take place. It is more difficult
to coagulate boiled milk with rennet than unboiled milk.

Experiment 51.