If
suitable apparatus is at hand, the transformation of electrical energy
into heat, light, sound, and mechanical motion can easily be shown.
4. A weight connected by a cord with some small machine and made to run
it, will help the pupil to grasp the general principles in the storage of
energy through gravity. A vessel of water on a high support from which the
water is siphoned on to a small water wheel will serve the same purpose.
5. The storing of energy by chemical means may be illustrated by
decomposing potassium chlorate with heat or by decomposing water by means
of a current of electricity.
6. Study the transfer of energy from the body to surrounding objects, as
in moving substances and lifting weights.
Fill a half gallon jar two thirds full of water and carefully take the
temperature with a chemical thermometer. Hold the hand in the water for
four or five minutes and take the temperature again. Inference.
CHAPTER XIII - GLANDS AND THE WORK OF EXCRETION
In our study so far we have been concerned mainly with the introduction of
materials into the body. We are now to consider the removal of materials
from the body. The structures most directly concerned in this work are
known as
*Glands.*--As generally understood, glands are organs that prepare special
liquids in the body and pour them out upon free surfaces.
Pages:
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273