as it exhibits the same properties, if separated from its combination. But it is incorrect to suppose that the carbon, hydrogen, and oxygen in sugar are identical with those in acetic acid, for there is a great difference between sugar and acetic acid ; and we cannot attribute this difference to anything but to the difference of the forces by which the same substance is governed. Thus, the carbon, hydrogen, or oxygen is not in any two cases supplied with the same properties. They assume in each substance a peculiar form. The general idea comprehending carbon, hydrogen, or oxygen in sugar and acetic acid, must therefore be modified, because the forces peculiar to matter must necessarily be modified, as matter is itself unalterable.
"This will appear clearly, if we consider the combinations of carbon with hydrogen. If we supposed the carbon and the hydrogen in C5H4, C10H8, C151-P2, C20H16,, to be always the same, we should be constrained to assume the identity of the substances, and any distinction would be impossible. Among the elements we know a considerable number which, without entering into any combination, present an entirely different appearance, in consequence of but a slight difference in the circumstances under which they are placed. For example, phosphorus becomes black when heated and then suddenly cooled; and by means of a red heat silica is so modified, that the substance, after and before the application of such heat, might be taken for two different substances, if we looked to its properties only. The interesting experiments recently made by Berzelius as to the allotropic character of phosphorus, have opened a new path for scientific investigations. If the simple substances can assume the permanent appearance of unlike bodies, without forming any combination, their compounds can do so much more. And such an assumption of other' characters must take place in all cases, in which no other mode remains of explaining the diversity of the compounds, than in the supposition of a real difference in the component elements them-selves."
Our former illustration of letters may help us to an explanation of isomerism, which is erroneously supposed to depend on a simple difference in the grouping of the elementary atoms, and not on a difference also of synthesis. Thus, in Stoekhardt's work on Chemistry we see isomeric diagrams, in which the, atoms are differently arranged, to explain all the differences of phenomena; as if a difference to the eye carried with it all other differences !
Isomeric bodies, properly, defined, are bodies having similar elementary composition with dissimilar immediate synthesis; and in proof thereof, they not only form different compounds when united with similar bodies, bases or acids, but also it is now found they give different products when analyzed with sufficient precaution.* It is to be further noted that all these isomeric bodies are bodies having an organic origin ; many of them are actually organic, i. e., they are formed of several proximate principles.
There is another difference of composition, and one which demarcates Chemistry from Anatomy with sufficient precision to form of itself a ground for denying the propriety of such a science as Organic Chemistry. The difference I refer to is this : Inorganic substances are definite in their composition. Water, for example, whether as water, steam, or ice, is uniformly composed of 122 ounces of hydrogen to 100 ounces of oxygen. Quicklime, however prepared—from marble, limestone, chalk, or oyster-shells—uniformly contains 250 ounces of calcium to 100 ounces of oxygen. It is on this fact rests the brilliant atomic theory of definite proportions.
Not so Organic substances. Those which are specially Organic—those, I mean, which are not crystallizable are uniformly indefinite or indeterminate in their composition, That is one of their definitions. No chemical formula, precise in its equivalents, will serve to characterise absolutely an organic substance.
Not only is the elementary composition of organic substances very complex, the immediate c