How is the second kind of attraction, or that between the particles of bodies, subdivided?
Into the _attraction of aggregation_, or _cohesion_; and _chemical attraction_, or _affinity_. The former takes place between particles which are _similar_, and the latter between those which are _dissimilar_. All the operations of chemistry are founded upon the force of affinity which Nature has established between the particles of different kinds of matter, and which enables the chemist to produce _new_ compounds differing more or less from the substances by whose union they were formed.
Is it, then, necessary for chemists to understand the relative nature of all substances?
Yes; because the basis of this science consists in an _analytical_ examination of the works of Nature; an investigation of the properties and uses of all substances we are acquainted with; and the study of the effects of _heat_ and _mixture_, in order that we may find out their general and subordinate laws.
_Investigation_, act of searching, or tracing out.
_Subordinate_, inferior in nature, dignity or power.
Relate a few more of the advantages obtained by a knowledge of Chemistry.
Many of the wonderful operations of Nature, and the changes which take place in substances around us, are, by its means, revealed to us. In every manufacture, art, or walk of life, the chemist possesses an advantage over his unskilled neighbor. It is necessary to the farmer and gardener, as it explains the growth of plants, the use of manures, and their proper application: and indispensable to the physician, that he may understand the animal economy, and the _effects_ which certain _causes_ chemically produce; and the nature of animal, vegetable, and mineral poisons. The study is, therefore, an invaluable branch in the education of youth: it is useful, not only in the active, but the _moral_ life, by laying the foundation of an ardent and inquiring mind. Even an everyday walk in the fields can be productive of instruction, by a knowledge of it;--and let us always remember, that "Knowledge is Power."
_Indispensable_, necessary, not to be done without.
ATTRACTION, TIDES, GRAVITY, ARTESIAN WELLS, AIR, ANEROID BAROMETER, EAR-TRUMPET, STETHOSCOPE, AUDIPHONE, TELEPHONE, PHONOGRAPH, MICROPHONE, MEGAPHONE, TASIMETER, BATHOMETER, ANEMOMETER, CHRONOMETER.