What a clamor and a protest would not these words have called forth had Leo XIII. written them in one of his Encyclicals! Burke has expressed a sentiment which they almost over-color in language far more beautiful.

He de

scribes the English people of his own day as thinking themselves bound "in their corporate capacity to perform their national homage to the institutor, and author, and protector of civil society. . . . They conceive," he says, "that He who gave our nature to be perfected by our virtue, willed also the necessary means of its perfection. He He willed willed therefore the State.

it in connection with the source and original archetype of all perfection." And thus the State itself becomes not, as Zarathustra terms it, a mere “refuge of the superfluous," but "a worthy offering on the high altar of universal praise."

Yet that is not all. Mr. Spencer informs us that

* Spencer, "Autobiography," ii. 467. * Burke, ii. p. 370.

Habemus confitentem. The agnostic, in these remarkable passages, and the rest which I cannot here set down, proclaims that religion, as it is an everlasting, in like manner is it a social necessity. The empty negative, which leaves only a "cosmic process" of devouring and devoured, will create and sustain nothing human. On the other hand, it cannot fail to produce, as we may see for ourselves in the nations that suffer from it, and as Spencer lamented, an "indifference to everything beyond material interests and the superficial aspects of things." Ignorance of God lies at the root of social anarchy. It is fatal to genius. It has no words of condemnation for prudent vice. It has never yet convinced the pleasure-seeker that he had any duty to others except to get enjoyment out of them. The evidence is abundant and is accumulating that the agnostic negation is not simply negative. Under its influence, precepts most positive, shaping the creed of no small number, have risen from the deeps. When we look at the ways of business, fashion, literature, and at social statistics, a new Decalogue appears in view. What are its commandments? I seem to read among them these: "Thou shalt make money, have no children, commit adultery, plead in the divorce court, and such duties done, commit suicide." Not the individual only, but the nation, if it loses its old Christian prejudices, will enter on this journey towards Hades. The test and proof that a mistake has been made by our agnostic philosophers are to be found in the national decay which follows on their teaching, as darkness follows on eclipse. And by national decay nothing else is meant than the suicide of the race, consequent on frauds in mar

10 Spencer, "Autobiography," p. 469.

riage, a dwindling birth-rate, unlimited divorce, degeneracy in offspring, the abuse of stimulants and of pleasure, the clouding of intellect, all which are fated to terminate in one disease-the denial of the will to live. Professor Huxley, to hinder this consummation, falls back on Christian ethics, which cannot flourish when the Gospel has been rejected. Mr. Herbert Spencer concludes a life spent in preaching

The National Review.

agnostic science by affirming its bankruptcy in the past, its hopelessness in the future. We could not wish for a conjunction of proofs more formidable and more unexpected in support of Burke's great political axiom, that "the institutor, and author, and protector of civil society" is One whom our modern teachers refuse to have in their knowledge.

William Barry.

To those who cull their knowledge of current science partly, at least, by means of occasional glances at more or less distorted images of single facets, such as are to be seen from time to time in the columns of the daily papers, I fear the title of this article may suggest that it is somewhat belated. Atoms! I hear them say, what is he thinking about? There are no atoms now, they have all been cut up into electrons and corpuscles. Who cares about the weights of the atoms at the beginning of the twentieth century?

And yet never, perhaps, since Dalton propounded his atomic hypothesis a century or so ago has the existence of these hypothetical particles seemed quite so probable, quite so believable as to-day. True it is that within the last few years some of our ideas about the chemical atoms have been modified profoundly. The hydrogen atom is no longer considered the smallest particle. If radium be indeed an element-and no one can deny that it exercises many of the functions of an element-then the atoms of Dalton can no longer be regarded as indestructible individuals, but rather must be looked upon as congeries of still smaller bodies, each atom forming a kind of diminutive heavenly system, so to speak, such as we might picture to ourselves by think

ing about what we should see, or of what we should not see, if we gazed upon the heavens through the wrong end of an immense and powerful telescope. Yet, after all, the idea of the chemical atom remains, and the part it plays is not less but even more important than of yore. Still, the basis of most chemical speculation, the hydrogen atom, now, in addition, affords the physicist a jumping-place, whence he may start on some of his amazing flights into the regions where matter, energy, and electricity dissolving, as it were, into one another, almost escape the scrutiny even of his penetrating glances.

Here, then, is my excuse-and you have only to read Professor J. J. Thomson's lecture on "Bodies smaller than Atoms" to see that it is a good excusefor asking the readers of the Cornhill to hark back, and dwell for a moment on such an old-time subject as the methods of weighing the chemical atoms.

In the last number of the Cornhill I endeavored to give those who are interested in matters of this kind a peep into the processes by which science has succeeded in weighing the earth, the sun, and other members of the heavenly constellations. The great difficulty, or rather one of the great

difficulties, in weighing the earth is its bigness. We not only cannot by any means get the earth into a scale pan, but we cannot even form a mental picture of such a process. When we contemplate the exploit of weighing an atom our difficulties are of the same order, but of the opposite kind. For atoms, if they exist, are far too small to be isolated. Think how many chemical atoms go to make up a single cubic centimètre of water, that is about as much as would go inside the shell of a small filbert, say, about 90,000,000,-, 000,000,000,000,000 (ninety thousand million billion), and you will realize the nature of the task which John Dalton, of Manchester, presented to science when, by formulating his Atomic Theory, he made it an object to determine the sizes and masses of the atoms of the elements. How were Davy, Wollaston, and their colleagues, expert experimenters though they were, to perform a feat like this with the means then at their disposal? How were they to weigh bodies that could not be seen by means of the most powerful microscopes, nay, to be exact, bodies which very possibly might exist only in the minds of Dalton and his followers? Let us see how this task has been accomplished.

From the earliest times philosophers have pondered on the constitution of matter. Does everything consist of grains held together by some attracting force, or is matter continuous, homogeneous, much as a jelly seems to be to the human eye? That is the question. The poet-philosopher Lucretius and others among the ancients, and in more recent days the great Newton, ranged themselves on the side of the atoms; the latter declaring that to him it seemed probable "that God in the beginning formed matter in solid, massy, hard, impenetrable, movable particles, ... and that these primitive particles, being solids, are incomparably harder

than any porous bodies compounded of them; even so very hard as never to wear or break in pieces, no ordinary power being able to divide what God Himself made one in the first creation." And, finally, John Dalton, the greatest of the "Atomists" as those who upheld the grained structure theory of matter were once designated, placed the atomic hypothesis on a firm foundation by showing how it might be applied to the elucidation of chemical phenomena.

Let it be admitted that the matter of the universe is composed of minute, invisible particles, which have never been broken down or destroyed in the various physical and chemical changes to which we have subjected them, except conceivably in certain special cases connected with radio-active change. Let it be admitted, further, that there are as many kinds of atoms as there are chemical elements, say, about eighty, and that the weight of the atom of each element differs from that of the atom of every other element known to us. Then the question is, How can we compare the weights of these eighty different kinds of atoms?

Dalton himself made courageous attempts to solve this problem. But he was at a great disadvantage. He was able to give us reasons for thinking that the weights of the atoms of different elements are unequal, but to weigh them correctly was not yet possible in his time. In some cases he was able to state, approximately, the proportions in which the better known elements combine. He knew, for example, that in water one part of hydrogen is united with eight of oxygen. But Dalton and his colleagues could not tell us whether these proportions of hydrogen and oxygen correspond to the union of one atom of hydrogen with one atom of oxygen or to the union of two atoms of hydrogen

1 Dalton's value was somewhat lower than this.

with a single atom of oxygen, or to some other more complicated arrangement. And thus for a long time but little progress was made, except perhaps in Italy, where the delicate perceptions of Avogadro enabled him, as early as 1811, to recognize the existence of a silken thread which might have guided us into the right path many years before most of the chemists actually walked there.

Is it not plain that if all matter consists of minute indivisible particles which conform to a very limited number of types, and if all the thousands of compounds known to chemists are produced by the joining together of these atoms in various numbers, then there must be two distinct classes of particles to be considered-first, the atoms, and, secondly, various groups of atoms; each particular group probably corresponding to a given element, or to a given compound substance? In these latter groups, the molécules intégrantes of Avogadro as distinguished from the molécules élémentaires or atoms, we have the molecules of the modern chemist.

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The obvious distinction between the atoms and molecules of the gaseous elements was recognized by Avogadro and Ampère at a very early stage. But it so happened that in their hands it was only fruitful when applied to the gases. And thus a quarter of a century elapsed before their ideas on this subject, and before Avogadro's mous hypothesis on the constitution of the gases, which teaches us that "in all elastic fluids"-gases-"observed under the same conditions the molecules are placed at equal distances," bore their predestined fruit in the hands of his eminent successor, Jean Baptiste André Dumas and of those who followed him.

As it would be impossible within the limits of half a score pages to give even a passing glance at the individual la

bors of the small army of chemists who have struggled with the problem of weighing the atoms, we will now drop the historical details of our subject, and turn our attention to its broader aspects.

Let us see exactly where we stand. According to the teachings of Avogadro, Ampère, Dumas, and the modern chemist, matter exists in two distinct states of subdivision. First, there are the atoms, which as far as we know are quite indivisible by chemical means. Secondly, there are groups of atoms held together by some kind of attraction, and constituting the larger particles called molecules-a definite group corresponding to each element and to each compound; the distinction between elementary and compound molecules in terms of the atomic hypothesis being this, that in each of the former all the atoms are similar, and that the molecule may even consist of a single atom, whilst the molecules of compounds must contain, every one of them, atoms of at least two different kinds. Then, in addition, Avogadro's hypothesis teaches us that equal volumes of gases, if measured at the same temperature and pressure, contain equal numbers of molecules. This last statement is not absolutely true, but it approaches the truth sufficiently nearly for our purpose. It holds equally when applied to elementary gases like oxygen and hydrogen and to compounds like steam, which is composed, as we know, of oxygen and hydrogen, provided that the steam is really in the gaseous state, that is, if it is at a sufficiently high temperature.

Now, what Avogadro's hypothesis does for us is this. It enables us to get round the difficulty created by the excessive minuteness of atoms and molecules. Because if equal volumes of two gases contain equal numbers of molecules, then from the behavior of these equal volumes, or of any other

known volumes of these gases, when they react with one another or with other gases, we can draw conclusions as to the behavior of single molecules. For example, under suitable conditions two volumes of the gas hydrogen will combine with one volume of oxygen, and produce two volumes of water in the form of steam. It does not matter what volumes are taken; they may be cubic inches, pints, gallons, cubic centimètres, what you will, provided that they correspond to the proportions mentioned above.

Now suppose that in a given case the one volume of oxygen contained one billion molecules of oxygen. Then would it not follow from Avogadro's hypothesis that the two volumes of hydrogen contained two billion molecules of hydrogen, and that the two volumes of steam produced by their combination contained two billion molecules of steam?

But if this is so, then one billion molecules of oxygen will unite with two billion molecules of hydrogen and yield two billion molecules of steam; or, dividing each of these numbers by one billion, we find that one molecule of oxygen will unite with two molecules of hydrogen and produce two molecules of steam.

Thus, the hypothesis affords us a bridge, as it were, by which we can pass from large volumes of gases which we can handle to the minuter molecules, which individually are invisible, intangible, and only to be clearly conceived, in fact, by the exercise of a well-trained imagination.

Before we proceed to apply the teachings of Avogadro in our attempt to solve the problem of weighing an atom, there is one other illustration which will help us to realize its value. It is easy to see that in each molecule of a compound there must be at least one atom of each constituent element, and, accordingly, that such molecules must

be made up of two, three, four, or some larger number of atoms. But it is by no means equally easy to form an opinion about the molecules of the elements; to decide, for example, whether these consist of single atoms or of pairs, of triplets, or of yet more complex groups. Now this is a question of considerable importance.

We know, as has already been explained, that one volume of oxygen will combine with two volumes of hydrogen and produce two volumes of steam, or, substituting as before molecules for volumes, that a molecule of oxygen will unite with two molecules of hydrogen and yield two molecules of water in the form of steam. This tells us just what we want to learn. For since there must be at least one atom of oxygen in each of these two molecules of water-that is, two atoms of oxygen in the two molecules of water taken together-it is clear that the molecule of oxygen from which they were produced must itself have contained at the very least two such atoms, for it would be inconsistent with the whole body of chemical knowledge to suppose that a single atom of any kind is created in the course of any chemical change. similar experiments, supplemented by similar reasoning, we can arrive at the constitution of other elementary molecules, and we find that while hydrogen molecules and many others are diatomic like oxygen, others again are differently constituted, some, e.g. ozone, the more active phase of oxygen, being composed of three atoms, others of four, and so on; whilst some, for example quicksilver and argon, have molecules which are composed of single atoms.

By

Before we may hope to follow the processes, simple as they are in principle, involved in weighing an atom, we have still to gain a really definite idea of what it is we want to weigh.