, so as not to mix
the white with the yolk. Drop about half a teaspoonful of the raw white of
egg into half a pint of distilled water. Beat the mixture vigorously with
a glass rod until it froths freely. Filter through several folds of muslin
until a fairly clear solution is obtained.

Experiment 32. To a small quantity of this solution in a test tube
add strong nitric acid, and boil. Note the formation of a white
precipitate, which turns yellow. After cooling, add ammonia, and note that
the precipitate becomes orange.

Experiment 33. Add to the solution of egg-albumen, excess of strong
solution of caustic soda (or potash), and then a drop or two of very
dilute solution (one per cent) of copper sulphate. A violet color is
obtained which deepens on boiling.

Experiment 34. Boil a small portion of the albumen solution in a test
tube, adding drop by drop dilute acetic acid (two per cent) until a flaky
coagulum of insoluble albumen separates.

Experiments with Starch.

Experiment 35. Wash a potato and peel it. Grate it on a nutmeg grater
into a tall cylindrical glass full of water. Allow the suspended particles
to subside, and after a time note the deposit. The lowest layer consists
of a white powder, or starch, and above it lie coarser fragments of
cellulose and other matters.

Experiment 36. Examine under the microscope a bit of the above white
deposit. Note that each starch granule shows an eccentric hilum with
concentric markings. Add a few drops of very dilute solution of iodine.
Each granule becomes blue, while the markings become more distinct.

Experiment 37. Examine a few of the many varieties of other kinds of
starch granules, as in rice, arrowroot, etc. Press some dry starch powder
between the thumb and forefinger, and note the peculiar crepitation.

Experiment 38. Rub a few bits of starch in a little cold water. Put a
little of the mixture in a large test tube, and then fill with boiling
water. Boil until an imperfect opalescent solution is obtained.

Experiment 39. Add powdered dry starch to cold water. It is
insoluble. Filter and test the filtrate with iodine. It gives no blue
color.

Experiment 40. Boil a little starch with water; if there is enough
starch it sets on cooling and a paste results.

Experiment 41. Moisten some flour with water until it forms a tough,
tenacious dough; tie it in a piece of cotton cloth, and knead it in a
vessel containing water until all the starch is separated. The