Nature’s Chemistry--Changes produced by Chemical Combination--Atomic Constitution of Bodies--Laws of Combination--Combining Equivalents--Elective Affinity--Chemical Decomposition--Compound Character of Chemical Phenomena--Catalysis or action of Presence--Transformation of Organic Bodies--Organic Chemistry--Constancy of Combining Proportions--The Law of Volumes, the Law of Substitutions, Isomeric States, &c. All things on the earth are the result of chemical combination. The operations by which the commingling of molecules and the interchange of atoms take place, we can imitate in our laboratories; but in nature they proceed by slow degrees, and, in general, in our hands they are distinguished by suddenness of action. In nature chemical power is distributed over a long period of time, and the process of change is scarcely to be observed. By art we concentrate chemical force, and expend it in producing a change which occupies but a few hours at most. Many of the more striking phenomena of nature are still mysterious to us, and principally because we do not, or cannot, take the element time into calculation. The geologist is compelled to do this to explain the progress of the formation of the crust of the earth, but the chemist rarely regards the effects of time in any of his operations. The chemical change which within the fissure of the rock is slowly and silently at work, displacing one element or molecule, and replacing it by another, is in all probability the operation of a truly geological period. Many, however, of the changes which are constantly going on around us, are of a much more rapid character, and in these nature is no slower in manipulating than the chemist.