upon its axis, their courses would be due north sizes, figures, and with such other properties, and south respectively; but in consequence of this and in such proportion to space, as most conrotation, which gives a greater velocity to those duced to the end for which he formed them; portions of the earth's surface which are near the and that these primitive particles, being solids, equator than to those which are more remote, are incomparably harder than any porous bodies these winds have, relatively to the surface over compounded of them; even so very hard as which they blow, a motion from east to west. never to wear or break to pieces; no ordinary Hence the trade winds appear as north-east winds power being able to divide what God himself in the Northern and south-east in the Southern made one in the first creation.' [MOLECULE.] hemisphere. The heated air which ascends at the ATOMIC THEORY, in chemistry, sometimes equator flows over northwards and southwards, termed the law of combining proportions. This and in its progress towards the poles becomes, in very important theory, founded on well-ascertained consequence of the earth's rotation, a south-west facts, has bestowed on modern chemistry an almost wind in the Northern hemisphere, and a north-west mathematical degree of precision. The theory, wind in the Southern. which is to be distinguished from the experiAn exceedingly interesting work on the subject mental part of the subject, supposes that chemical of this article is The Atmosphere, translated compounds result from the combination of the from the French of Camille Flammarion, edited ultimate atoms of their constituent parts. It has by James Glaisher, F.R.S.; London, 1873. Its been determined by experiment, and the fact object is to give a broad outline of the causes serves as the basis of the theory, that a compound which give rise to facts of every-day occurrence body, when pure, always contains the same proin the atmosphere, in such a form that any reader who wishes to obtain a general view of such phenomena and their origin is readily enabled to do so. ATOLL is a name given by the natives of the Maldive Islands to the detached coral formations of which their Archipelago is composed.

portions of its constituents: thus calcareous spar, and the pure part of marble, chalk, and lime

stone, consist of carbonate of lime, composed of the carbonic acid always contains uniform quanuniform proportions of carbonic acid and lime; tities of carbon and oxygen, and the lime uniform proportions of calcium and oxygen. The same ATOM, or ATOMS (äropo), the ultimate and law also exists with regard to all similarly-conindivisible particles of matter, from a Greek com- stituted oxides, sulphurets, and salts, and indeed pound, signifying indivisible. as to all chemical compounds whatever, whether Leucippus, a philosopher of Abdera, is generally presented to us by nature or formed by art. This regarded as the original propounder of what has is a simple statement of the fundamental facts been called the atomic philosophy. It was upon which the superstructure of the atomic theory adopted by Democritus, in his Cosmogony;' has been raised. and afterwards by Epicurus, to whom its cele- The earliest experiments which could have brity is chiefly owing. The general bearings of served as a basis for the atomic theory were those this theory, as illustrated in Dr. Good's Book of of Wenzel, a German chemist, who published, in Nature,' are as follow:-Matter and space existed 1777, a work' On the Affinities of Bodies;' the from eternity. Matter is formed of minute atoms, experiments detailed in it, though neglected at solid and indivisible, the shape of the atoms vary- the time, are now acknowledged to possess a very ing in different species of matter, and each species considerable degree of accuracy. The author having certain intrinsic powers of motion which pro- showed that, when any two neutral salts decomduced the phenomena of the universe. Infinite posed each other, the resulting new compounds groups of these atoms, flying through space by vir- were exactly neutral. In 1786 Dr. Bryan Higtue of their intrinsic motions, and meeting each gins published a Treatise on Acids and Air,' in other, have, by their varied forces and qualities, com- which he contended that elastic fluids unite with bined to form the various solids, liquids, and vapours each other in limited proportions only, that their of which the world consists. No physical sub- atoms are surrounded by an atmosphere of fire, stances are permanent, for there are fresh tides of which makes them repulsive of each other. A atoms always approaching to replace those which fly relation of this writer, Mr. William Higgins, off. Space is infinite, material atoms are infinite, published in 1790 a Comparative View of but the world is not infinite. This, then, is not the Phlogistic and Antiphlogistic Theories,' in the only world, nor the only material system that which he spoke of several definite compounds of exists. The cause that has produced this visible azote with oxygen, and threw out a suggestion system is competent to produce others: it has been that water was probably formed of definite proacting perpetually from all eternity; and there portions of two gases, which are now known to are other worlds, and other systems of worlds, be oxygen and hydrogen. existing around us.' [ANAXAGORAS.]

In 1792, Richter, a Prussian chemist, pub

During the most flourishing periods of the lished a work called Elements of Stochiometrie, Greek philosophy, this doctrine of matter consist- or the Mathematics of the Chemical Elements." ing of an assemblage of indivisible particles seems This author treated the subject almost in the same to have kept its ground under various modifica- way as Wenzel had previously done, but extended tions. Newton's opinions were as follow: All it very considerably; he endeavoured to deterthings considered, it seems probable that God mine the capacity of saturation of each acid and in the beginning formed matter in solid, massy, base, and to indicate by numbers the weights hard, impenetrable, movable particles, of such which mutually saturate each other. He pul

lished a table of these, but, though the attempt | protoxide; or whether that which contains most was new and exceedingly ingenious, the results is a protoxide or a peroxide. These are points were far from accurate. The discoveries of Proust, which can be determined only by comparison; a French chemist who was professor of chemistry but, as a general rule (subject to a few exceptions), at Madrid, are well worthy of notice, he being it is found that the metallic oxide which contains the first person who attempted an accurate ana- least oxygen is the protoxide, and that that weight lysis of metallic oxides. He found that metals of the metal which combines with 8 by weight unite only with determinate proportions of oxygen, of oxygen, denotes the weight of its atom, and that the same law applied to sulphur and the their united weights that of the oxide. metals, and that these proportions might be stated in numbers. His opinions were strenuously opposed by Berthollet, but their accuracy is now generally admitted.

In the year 1803 the late Dr. Dalton explained in the Manchester Memoirs' his views concerning the chemical constitution of bodies; and in 1808 he published his 'New System of Chemical Philosophy.' He introduced the doctrine of multiples, and expressed by simple numbers the combining weights of bodies. He announced it as a general rule, that when only one combination of two bodies can be obtained, it must be presumed to be a binary one, unless some cause appear to the contrary.' Consistently with this law, and correctly at the time it was written, Dalton regarded water as a binary compound of hydrogen and oxygen, and the relative weights, since corrected, are considered as one to eight. As, then, water consists of an atom of hydrogen and an atom of oxygen, either of these elements may be selected as unity. Dalton fixed on hydrogen, because it is that body which unites with others in the smallest proportion; thus, then, we have water composed of one of hydrogen by weight, or one atom; and eight of oxygen by weight, or one atom; and in all cases an atom of hydrogen being represented by 1, an atom of oxygen will be represented by 8; and these being the atomic weight of the elements, that of the compound will be obtained by adding them together, thus

Hydrogen 1 atom = 1
1 atom = 8

Oxygen

Water

1 atom = 9

In the compounds of oxygen and copper the second portion of that element which unites with the same quantity of the metal, is double the first. Now upon this and numerous similar facts is founded one of the most important and beautiful peculiarities of Dalton's theory, sometimes described as the doctrine of multiples. In the case just alluded to, the second portion of oxygen is precisely double the first; but there are some cases in which the greater proportions are not multiples of the less by any entire number. For example, there are two oxides of iron, the relative combining weights of which are such as to show that one, the protoxide, consists of 1 atom or combining equivalent of metal to 1 atom of oxygen; while the other, the peroxide, consists of 2 atoms of metal to 3 of oxygen. Again, there are three oxides of lead, of which the relative quantities of the elements are such as are best explained by supposing that the protoxide consists of 1 metal and 1 oxygen, the peroxide of 1 metal and 2 oxygen, and the red oxide of 2 protoxide and 1 peroxide, or 3 metal and 4 oxygen. Among the most remarkable combinations are those of manganese and oxygen, of which there are five varieties, all of which are resolvable into the protoxide and the peroxide; and those of nitrogen and oxygen, in which 1 atom of nitrogen combines, in five different substances, with 1, 2, 3, 4, and 5 atoms of oxygen respectively.

While in some cases the hydrogen and in others the oxygen standard is assumed, there are others in which they may be employed indifferently; thus, of carbon 6 parts by weight is the largest quantity which combines either with 1 part by weight of hydrogen, or 1 atom, or with 8 parts The weight, then, of a compound atom is ob- by weight of oxygen, or 1 atom; 6 is therefore tained by adding together the atomic weights of the atomic weight of carbon. But in respect to its constituents. As all the other elements unite sulphur, nitrogen, and a few other elements, it is either with hydrogen or with oxygen, the hydrogen found more convenient to take oxygen than or the oxygen standard may be used according to hydrogen as the standard of comparison. Somecircumstances, considering the former to be 1, times the two elements combine in a compound in and the latter 8. The compounds of any given such proportions as to lead to the supposition of element with many other elements must be exa-half atoms being employed; an absurdity in mined, before the combining number of the former terms, for the atom is presumed to be indivisible. can be correctly determined; or, as Dalton ex- A sesqui-carbonate of potash is formed, according presses it, it is necessary not only to consider to this view, of 14 atoms acid, and 1 atom base; the combinations of A with B, but also those of but the atom is got rid of by viewing the conA with CD E, &c., as well as those of B with stitution of the salt as being 3 atoms acid + CD, &c., before we can have good reason to be 2 atoms base, with a combining weight double of satisfied with our determination as to the number that resulting from the other mode of interpretaof atoms which enter into the various compounds.' tion. These sesqui compounds were long under exVarious compounds of the same two elements amination by chemists, with a view of solving the may exist; and supposing an elementary body, as difficulty. copper or silver, united with two proportions of The following diagram will illustrate the mode oxygen, various questions may arise as to the in which the atomic numbers or combining constitution of the resulting oxides; as, whether weights retain their character throughout all the that which contains least oxygen is a suboxide or compositions or decompositions which may take

Nitrous oxide

By Volume. Nitrog. Oxygen. 2

By Weight. Nitrog. Oxygen.

14

8

2 2

14

16

14

24

14

32

14 40

Nitric oxide
Hyponitrous acid 2
Nitrous acid
Nitric acid

2

2

place. An atom of nitric acid (hydrogen being|1 to 3, &c., are those of oxygen and nitrogen, taken as 1, and oxygen as 8) weighs 54, and thus:one of barytes 76, forming when combined 130 of neutral nitrate of barytes; an atom of neutral sulphate of potash=88, is composed of an atom of sulphuric acid=40, and an atom of potash=48. Now when an atom of nitrate of barytes=130, dissolved in water, is mixed with an atom of sulphate of potash=88, in solution, double decomposition ensues, and two new and perfectly neutral salts are formed, viz. 1 atom of nitrate of potash=102, consisting of an atom of nitric acid=54, and an atom of potash=48. This remains in solution; and there is precipitated an atom of neutral sulphate of barytes=116, composed of 1 atom of sulphuric acid=40, and 1 atom of barytes=76.

Dr. Prout and Dr. Thomson inferred, from these results, that the atomic weights of bodies are multiples of the atomic weight of hydrogen by a whole number. But this view was not acquiesced in by all chemists. Dr. Turner considered that the simple ratio in which volumes combine appears to indicate a close correspondence in the size of the atoms of gaseous bodies. It naturally sugSulphate gests the idea that this peculiarity may arise from the atoms of elementary principles possessing the same magnitude. On this supposition, equal measures of such substances in the gaseous form, at the same temperature and pressure, would probably contain an equal number of atoms; and the specific gravity of these gases would depend on the relative weight of their atoms. The same Dalton's theory, in the first instance applied by elementary principles in the gaseous state would numbers which indicate the specific gravity of him more particularly to the composition of then express the relative weight of their atoms, so gaseous bodies, was greatly extended by Wollas- that the latter would be ascertained by means of ton in 1808, in respect to super-acid and sub-acid the former, or the atomic weight of a solid or salts; and in 1814 the same distinguished philo- liquid represent the specific gravity of its vapour. sopher published his 'Scale of Chemical Equiva- The proportional numbers adopted by Sir H. lents,' by which the atomic numbers of compound Davy in his Elements of Chemical Philosophy, bodies could be roughly computed almost at a and the atomic weights employed by Berzelius in glance. About 1808 the Swedish chemist Ber- his 'System of Chemistry,' were selected in aczelius also engaged in a series of researches re-cordance with this view. Thus, water, being specting combining weights, in which he arrived formed of two measures of hydrogen and one at results bearing out, for the most part, those deduced by Dalton.

116 Sulphate of Barytes.

measure of oxygen, is believed by Berzelius to In 1809 Gay-Lussac published an important of the latter; and, for a similar reason, he regards consist of two atoms of the former, and one atom memoir on the Theory of Volumes,' in which the definite composition of compound gases was of nitrogen and one atom of oxygen. The atoms protoxide of nitrogen as a compound of two atoms placed in a new and instructive light. Suspect- and volumes of the four elementary gases-oxying, from the previously ascertained fact, that 100 volumes of oxygen gas combine with 200 volumes gen, chlorine, hydrogen, and nitrogen-are thus made to coincide with each other. This method, of hydrogen gas to form water, that other gaseous though perhaps preferable to any other, has not bodies would be found to unite in simple propor- hitherto been generally followed. Most chemists tions, he prepared muriatic, carbonic, and fluoboric consider water, protoxide of chlorine, and protacid gases, and combined them with ammoniacal oxide of nitrogen, as containing each one atom gas, and he found that they united in the follow of their elements; and, consequently, as those ing proportions:compounds consist of one measure of oxygen united with two measures of the other consti100 muriatic acid gas with 100 ammoniacal gas. tuent, an atom of hydrogen, chlorine, and nitro100 carbonic acid gas 100

All the four terms, atom, equivalent, proportion, Fluorine proportional, have had their advocates; but it is Glucinum. necessary simply to bear in mind that what is meant Gold . is the relative weights in which chemical substances Hydrogen. combine, without necessarily involving any theory Ilmenium.

as to the ultimate molecule state of matter.

Iodine.

132

15

0.125

atom, oxy. 100 hydrog.

12.4795 Copper*

Cu

8

8

8

...

19.00
6.97

...

237.50

87-12 1229.16 12.50

The atomic theory of chemical elements has Iridium been the subject of some remarkable modifications Iron* in recent years. The term Isomorphism has been Lantanium applied to a law or principle which connects cer- Lead* tain crystals into a group: if the same number of Lithium atoms are combined together in the same way, the Magnesium same form of crystals is produced, whatever may Manganese be the atomic weights or the chemical nature of Mercury*. the individual atoms. The term Dimorphism has Molybdenum . been applied to a property assumed by some bodies Nickel. of presenting two totally distinct forms under Niobium different circumstances, although no change can Nitrogen be detected in their atomic constitution. Again, Osmium the term Isomerism has been suggested to repre- Oxygen sent a similarity of atomic constitution in two or Palladium more bodies, although those bodies differ widely Pelopium . in appearance and in character.

Phosphorus
Platinum .
Potassium'
Rhodium

If the principle be admitted that all atomic weights are multiples by whole numbers of the atomic weight of hydrogen, it follows that all atomic weights whatever will be expressed in Ruthenium whole numbers, the number for hydrogen being 1; Selenium and this is the system followed in most English Silicon works on chemistry. But the exactness of modern Silver* analysis has shown that this mathematical relation Sodium" by no means uniformly holds its place; and it is Strontium deemed better to state the atomic weights actually Sulphur deduced by experiment. We subjoin a carefully- Tantalum. compiled tabular view of the elementary bodies, Tellurium. with the symbols by which they are now indicated. Terbium In the third column hydrogen is supposed to be Thorinum. = 1; in the fourth column, oxygen is 100:- Tin* .

ть

...

801-76

...

The symbols are used as an abbreviated form his priest, by refusing a ransom for his daughter, is of expression, and are at once understood by all not content with restitution, but proceeds to atone chemists; but as only a few of them are fami- for his fault by an offering, the purpose of which liarly known to general readers, they are used in is declared by Ulysses (Iliad,' i. 442)—' Agathe present work only when no ambiguity can memnon sent me to sacrifice a sacred hecatomb to occur. All organic compounds, derived from the Apollo in behalf of the Danai, that we may apanimal and vegetable kingdoms, are composed pease the Sovereign God.' almost wholly of four elements-oxygen, hydro- If we pursue our inquiries through the accounts gen, nitrogen, carbon; and it is therefore quite left us by the Greek and Roman writers of the sufficient to indicate such by the four initial let-barbarous nations with which they were acters O, H, N, C. In some of the more complex quainted, from India to Britain, we shall find the substances, where many atoms of different ele- same notion and similar practices of atonement. ments combine to form a compound atom, the It shows itself among the various tribes of Africa, number of each is attached to its symbol, either the islanders of the South Seas, and even that before or after it: thus, Benzoyle consists of three most peculiar race, the natives of Australia, either kinds of elements, and the Benzoyle atom is in the shape of some offering, or some mutilation formed of twenty-one elementary atoms-C14 of the person. Hs O2; or 14 C, 5 H, 2 O, implying fourteen of carbon, five of hydrogen, and two of oxygen. In such a case as this, the atomic constitution of the compound alone is given, and not the atomic weight of each element: it is only in the simpler compounds that the atomic weights need be repeated.

Sometimes greater condensation is produced by placing a dot for each atom of oxygen contained in a compound; the dot being placed over the symbol of the base with which the oxygen is combined. Thus, sulphuric acid, instead of being 03 S, becomes simply S, water is H, and protoxide of iron is Fe.

In reply to some allegations of defects in the atomic theory, a lecture was delivered on the subject, in 1869, by Professor Williamson, and printed in the Journal of the Chemical Society for that year. ATONEMENT, a certain mode of appeasing anger, and obtaining pardon for an offence. In the act of atonement there is commonly understood to be a substitution of something offered, or of some personal suffering, for a penalty which would otherwise be exacted. In theology, it has respect to offences committed against the Deity; it is in the theological acceptation of the term that it will be considered in the present article.

He con

It is all but universally acknowledged by the believers in revelation, that the Levitical atonements were, in part at least, typical of that one great sacrifice on which the Christian doctrine of the atonement is founded. We can do little more than state what is understood by the Christian when he speaks of the atonement. siders man, through a sinful nature, and practices and affections conformable to that nature, to have come into a state of alienation from God; in other words he believes that God is just and holy, that man has sinned, and must therefore be believes that the Divine Being, revealed to us punished. This being his condition, he further under the title of the Son of God, interposed between the sentence and its execution, suffered in our stead, and atoned by his death for our sin; that the immediate consequences were, remission of the original sentence, and restoration to a state which is still probationary, but in which man is made capable of a permanent reunion with his Maker. The believer in the doctrine of the atonement supposes that the sacrifice was necessary according to a law fixed in the counsels of God (which law he also supposes to be revealed to us), that sin must be atoned for before it can be pardoned. He supposes the knowledge of the fact to be necessary to the formation of the Christian character, and its moral consequences to be, a deeper sense of the turpitude of sin, and also a new and powerful motive to a love of the Supreme Being, supplying a remedy for that selfish principle which might prevail, if the only motives to obedience were the hope of reward and the fear of punishment.

The practice of atonement is remarkable for its antiquity and universality. In the oldest books of the Hebrew Scriptures we have numerous instances of expiatory rites where atonement is the prominent feature. In some cases the atonement was made for a specific offence (Levit. iv., Numb. xvi. 46); in others it had reference to a state of We have endeavoured to state the doctrine of the transgression. (Levit. xvi.) The Hebrew records atonement in such terms as would be accepted by contain also notices of the practice of atonement, all who accepted the doctrine itself on the auindependent of the Mosaic institutions, and un-thority of Scripture. connected with the religious opinions of the Hebrew people. To atone, according to the vulgar etymology, is The barbarous offerings to to set at one, that is, to reconcile; and hence Moloch appear in the light of atonements when the word atonement is etymologically explained interpreted by the indignant expostulation of at-one-ment. In the authorized version of the Micah (vi. 7)-Shall I give my first-born for my transgression, and the fruit of my body for the sin of my soul?'

New Testament the same word which in 2 Cor. v. 19 is properly rendered reconciliation, is in Rom. v. 11 rendered atonement. The word, however, soon came to bear the meaning in which it is now used; and such is in fact its ordinary meaning in the authorized version of the Old

At the earliest date to which we can carry our inquiries by means of the heathen records, we meet with the same notion of atonement. Agamemnon, having offended Apollo in the person of Testament.