A Catechism of Familiar Things; / Their History, and the Events Which Led to Their Discovery. / With a Short Explanation of Some of the Principal Natural Phenomena. For the Use of Schools and Families. Enlarged and Revised Edition.

by Anonymous

Give an example of the first kind of attraction.

One of the most familiar instances of attraction at sensible distances is seen in the descent of heavy bodies to the ground. When a stone is lifted up in the hand, the earth's attraction, which previously caused it to remain at its surface, is overcome; but, as soon as the hand is withdrawn, the stone falls to the earth. The force which causes this is called the attraction of gravitation, or simply gravitation.

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 dis-similar. 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.

Analytical, relating to analysis.

Investigation, act of searching, or tracing out.

Subordinate, inferior in nature, dignity or power.