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multiple of hydrogen, but is represented by 6.04, or some number approaching to 6.04. We can only, therefore, derive carbon from hydrogen, by ascending to a higher order of molecules, from which hydrogen itself is derived. Now, we may suppose that hydrogen is derived from two distinct orders of molecules, m and n. In this case, the first member of the series in the descending order is m+n; the second 2 m + n, or m + 2 n; the third 3 m + n, or m+ 3 n; and so on, until we reach x m + n, or m + x n=H or H1.

But if we assume that the properties of bodies are determined, not by differences in the nature of their pristine molecules, but by differences in their modes of combinations, or, in other words, in the relations in which they stand to one another, we may assume that hydrogen is derived from a single order of molecules m. In this case, m+ m becomes the second member of the series, m + 2 m the third, m+ 3 m the fourth, and so on in the descending order, until we reach H=1. But the series being still continued, H=1 combines with m, and forms 1 +m; 1+m combines with m, and forms 1+2 m; and so on, in an arithmetical progression, until we reach 1 + x m=6.04=C.

But we cannot determine the value of m from any known data ; for we do not know how far the division of matter may be carried. An opinion, supported by many mathematicians of the last age was, that matter was infinitely divisible. It must be conceded, that space is, mathematically, infinitely divisible, for, if space be divided by any given quantity, as 2, the half must be equally divisible by 2, and so on ad infinitum. But although space be infinitely divisible, it in no degree follows that matter is infinitely divided. We must suppose that there are limits to the division of matter; for otherwise we should involve ourselves in this conclusion, that to form a particle of matter in any finite degree exceeding an infinitely small particle, by the successive addition of its integrant parts, an infinite time would be

required. We may reasonably suppose, then, that there are limits to the division of matter, although these limits are unknown.

We cannot, however, as has been said, determine the value of the ultimate particle m.

But let us suppose, for the purpose of example, that the value, or atomic weight of m, is .01, then,

The 2d member of the series, m +.01 = .02
The 3d,
The 4th,
The 5th,
The 6th,
The 7th,
The 8th,
The 9th,
The 10th,
And so on to H

=1.00

= .03 = .04 = .05 = .06 = .07 = .08 = .09 =.10

Now, let us suppose the same series to be continued, and we shall arrive, in the descending order, at 6.04 = C. Thus, two definite bodies will have been formed, H and C; and from H and C, it has been seen, we can suppose every known body, and every possible combination, to be derived.

But we may suppose the series just given to be continued in the descending order, until we reach the number corresponding with oxygen.

I have admitted the possibility of this result, in the supposition made, that bodies may be conceived to be resolved into hydrogen, carbon, and oxygen, or into one or more of these bodies.

We might, upon the same principle, ascend to the higher degree of generalization, and assume all bodies to be derived from the unknown form of matter m. But, if hydrogen and carbon be derived from m, in a given series, the further conclusions to be drawn, are not invalidated, because we proceed from a lower degree of generalization.

Hydrogen, then, being the first of known bodies in the series from m, and carbon the second, we may derive all

the other bodies in the descending order from these two forms of matter, just as if we began at the higher stage of generalization, and derived them all, including hydrogen and carbon themselves, from m. Having obtained two known bodies H and C, we can suppose these two bodies to combine, and form the binary root HC, and from this root any number of combinations to be formed. Thus, HC combines with 1 equivalent of hydrogen, and forms H’ C, as shewn in the table before given. H2C combines with C, and forms H2 C?, representing; on the hypothesis, nitrogen. This, again, combines with hydrogen, forming H® C’, or with carbon, forming Ho C, and so on through the entire series of bodies which we term simple, and consequently through the entire series which we know to be compound. And the series of combinations, it is to be observed, is not interrupted when we arrive at the products of the organic kingdom. The essential constituents of this order of bodies are hydrogen, carbon, oxygen, and nitrogen, and two or more of these roots combining, constitute the compounds which the living world supplies. But all these substances may

be derived from the common root H C, so that the law of continuous combinations applies alike to the inorganic and organic kingdoms.

The term Organic Chemistry has been recently introduced ; but the term is illogical, for no branch of chemistry can be termed organic; and even when we employ the more correct expression, the chemistry of organic bodies, we may lead others into error unless we define our meaning. The principal constituents of living bodies, or bodies that have lived, are the four substances referred to, and these substances are common to both the natural kingdoms. The essential difference between the two classes of products, when we regard their chemical nature, is, that under the influence of the living principle, whatever the nature of this principle be, the roots of bodies enter into

combinations, which frequently cannot be produced by the common chemical agencies. But there is no other conceivable distinction between the two classes of products with respect to their nature and origin. They are all, we must suppose, derived from common roots, or, in other words, from the same kind of matter. Carbonic acid is no more a peculiar product of plants and animals than of minerals, and oxalic acid is merely a species of the same genus as carbonic acid, and cannot be placed in any other division of chemical compounds. Gum, starch, and sugar, are the products of plants, but are all resolvable into carbon, oxygen, and hydrogen, and, therefore, do not differ from the bodies of the inorganic kingdom, composed of the same elements, except in so far as these elements may be combined in different ratios. There can be no reasonable question, that, in either case, the constituent elements have arranged themselves, in the manner proper to each body, in conformity with the same chemical laws; and we may conclude, that the essential difference is, that the elements in the one case have obeyed the ordinary chemical affinities, and that in the other these affinities have been determined to a given end by another system of laws, to which, in our ignorance of their nature, we apply the term vital. When we, therefore, direct chemical researches to substances derived from bodies that have been once organized, we are in no respect to assume, that we have to do with a different order of matter, in so far as its chemical constitution is concerned,

Chemistry applied to the latter class of bodies, has, within our own times, made a surprising advance. But as yet this advance has been rather towards the collection of facts than towards the establishment of principles. Compound after compound is in the course of being added to the list, and no limit can be assigned to the number which may be produced. For not only may the four substances, hydrogen, carbon, oxygen, and nitrogen, into which the great mass of

substances of organic origin is resolvable, be combined in a vast number of ways; but the compounds thus produced may combine with, or be acted upon, by such bodies as chlorine, sulphur, phosphorus, arsenic, and by the acids and other compounds formed by these bodies. We must see, therefore, that there is no assignable limit to the number of compounds that may be produced by the action of so many substances upon one another. If we proceed, as now, in adding new compounds to those already known, we may expect that chemistry will become a chaos of names and unconnected results, which will overburden the memory, unless we shall be able to reduce the scattered truths to order. Chemists, indeed, engaged in this interesting branch of inquiry, have everywhere felt the necessity of arranging the results of their experiments into something like laws. Hence, the introduction of what have been termed radicals, or roots common to a number of compounds. To this species of arrangement no logical objection exists. On the contrary, it is founded on the application of a principle, which all the analytical researches of chemistry tend to confirm, the resolution of compound bodies into others more simple. But it may be gravely questioned, whether we are now proceeding in the right direction in our method of applying the principle to the formation of roots and chemical formulæ, and are not attempting to express more by these formulæ than our knowledge will warrant. A formula should be the expression of a chemical truth, as of the ratio in which certain elements enter into a given compound ; but we should be careful, in reducing this expression of a truth to another form, to express no hypothesis which is not necessarily involved in the truth to be expressed. Yet, if I mistake not, in our construction of these hypothetical formulæ by which we endeavour to express the nature of the numerous compounds which we are now enabled to form, we are passing far beyond the limits of a just induction. Not contented with expressing the ratios in which

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