Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. Excerpt from book: Section 3CHAP. III. ATTRACTION OF COHESION. Having adverted in a general way to the attractive power which the bodies of the universe exert upon each other; and having stated that this agency is exerted by the globe of the earth as well as by the smallest masses composing it, and that it gives origin to great varieties in the constitution of matter, it remains to enquire how far the minute particles of which these masses consist are affected by any attrative influence. If we examine the materials of the globe, we perceive that some are hard and dense; that others are soft and porous, that water is destitute of solidity; and that the atmosphere is far more attenuated. If a certain force be applied to a piece of glass, it is resisted; but if the force be increased, the glass is broken, and by repetition of the process may be reduced to powder. The glass is now separated into the parts which previously offered resistance to the change, and which, consequently, were held together by some force. This force, therefore, is the cause of the solidity of the glass: it was obviously an textit{attraction of the parts to.each other that caused them to cohere; and hence it is called the attraction of textit{cohesion. It is also called the attraction of textit{aggregation, because it aggregates or assembles and retains the particles of bodies in the state of a solid. The evidence of the existence of cohesion is not merely inferential from the constitution of solids, but can be proved to act between separate atoms and masses of matter. A mass of gold can be beaten out into a thin film, which could not happen if its constituent particles did not glide over each other and join new ones during the hammering; yet still they are found to cohere. Two distinct masses of matter may be made to cohere by contact. Thus, let two p...