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hot platinum-wire, which would otherwise give a continuous or complete spectrum, was passed through a flame of weak aqueous alcohol in which common salt was dissolved.
A still more striking proof of the same fact was shown in an ingenious experiment by Professor Roscoe in his lecture at the Royal Institution (partially frustrated, however, by an unfortunate breakage). A piece of sodium was placed in a glass tube exhausted of air, and then heated until the tube was filled with pure sodium vapour. When viewed by pure yellow sodium light this tube appeared nearly opaque, while by all ordinary light it was perfectly transparent !
But how are the conditions of these experiments fulfilled by the sun? Kirchhoff makes the very reasonable assumption, that the central solid and fluid mass of the sun gives off light rays of every character, such as would produce a continuous and complete spectrum, like that of incandescent platinum, but that the sun's atmosphere contains the gaseous elements which absorb certain definite rays, and produce Fraunhofer's lines. By these processes of experiment and inductive reasoning, Kirchhoff has already proved that the sun's atmosphere contains, amongst other substances, sodium, iron, magnesium, chromium, and nickel, but that lithium is not present in any appreciable quantity.
Indeed it wants little cool reasoning to be convinced of these statements when we see the spectra of the sun and of one of these elements side by side. Thus Professor Roscoe, in his lecture, eloquently described the indelible impression made on his mind by the splendid spectacle of the coincidence of the bright lines of the iron spectrum with a part of the dark solar lines:
“In the lower half of the field of the telescope were at least seventy brilliant iron lines, of various colours, and of all degrees of intensity and of breadth ; whilst in the upper half of the field the solar spectrum, cut up, as it were, by hundreds of dark lines, exhibited its steady light. Situated exactly above each of the seventy bright lines was a dark solar line. These lines did not only coincide with a degree of sharpness and precision perfectly marvellous, but the intensity and breadth of each bright line was so accurately preserved in its dark representative, that the truth of the assertion that iron was contained in the sun flashed upon the mind at once." In the whole range of the sciences there will scarcely be found an experiment so intrinsically beautiful in itself, or so pregnant with interesting information, as this. By the aid of such experiments the chemist will not always grovel on the earth. Light has now become his servant, and will bring him telegraphic information from every part of space.
The present occasion is not quite the first on which our thoughts have been raised to the chemical composition of as
tronomical bodies. The aerolites which occasionally fall upon the earth's surface from the unknown regions of space have been found to contain in greater or less quantity many of the terrestrial elements, such as iron, nickel, manganese, chromium, cobalt, aluminium, calcium, magnesium, sodium, silicon, sulphur, carbon, hydrogen, and oxygen. No new element unknown to us here has been found in these aerolites; but at the same time no combination of elements, such as the aerolites almost invariably present, has ever been met with among the plutonic or sedimentary rocks of our planet. Light itself has previously been made to yield some slight information by observations as to its state of polarization.
It is very uncertain to what extent we may be able, by observing the spectra of the stars, to determine their chemical composition. A statement of Sir J. Herschel bears closely on this matter, and is not very encouraging. He says :*
“Nothing short of a separate and independent estimation of the total amount of the red, yellow, and the blue rays in the spectrum of each star would suffice for the resolution of the problem of astrometry in the strictness of its numerical acceptation ; and this the actual state of optical science leaves us destitute of the means even of attempting with the slightest prospect of success."
But in spite of this we entertain no doubt that every principal star will, in the course of time, be analysed by spectrum observation, and that Bunsen will then be one of the chief founders of the Chemistry of the Universe, as he is already the chief contributor to the chemical geology of our own globe. In thus speaking we are not making random generalisations, but have facts to warrant what we say. Fraunhofer did not neglect the spectra of the stars, and has given us nearly the whole of the information we possess about them. In the spectrum of Sirius he observed no fixed lines within the orange and yellow spaces, but in the green there was a very strong streak, and two other very strong ones in the blue. The star Castor gave a spectrum exactly like that of Sirius, the streak in the green being in the very same place. The spectrum of Pollux contained, besides many other weak lines, a line corresponding to that of D in the solar spectrum. The line D was also seen in the spectra of the stars Capella, Betalgeus, and Procyon.t But observations of this nature are surrounded with difficulties such as even Fraunhofer, with his incomparable prisms and lenses, could scarcely overcome.
The interest of this subject is immensely increased if we consider that the colours of the fixed stars appear even to the naked
* Results of Astronomical Observations at the Cape of Good Hope, p. 304. † Brewster's Edinburgh Journal of Science, vol. viii. p. 7.
eye exceedingly various, pointing no doubt to great differences of chemical composition. Several astronomers, especially Sir J. Herschel, Admiral Smyth, Sestini, and Struve, have devoted much attention to this subject. Admiral Smyth states,* as the general results of the surveys made, that of 2540 stars, the yellow stars are about half the total number, and equally distributed; the white stars are one-fifth, in scattered portions; and the orange rather more than one-fifth. The red or the blue are rare from the Pole to 30° of north declination; the blue then become numerous (=+) to the equator, especially from right ascension 18 hours to 20 hours, and the red abound from 0° to 30° south declination and right ascension 16 to 20 hours. Sir J. Herschel gives a list of insulated stars of a red colour almost as deep as that of blood, and gives many interesting details concerning particoloured double or multiple stars. He believes, however, that no green or blue star (of any decided hue) has been noticed unassociated with a companion brighter than itself.
A solitary observation of the spectrum of a coloured star, & Herculis, is recorded by Brewster, who, for this purpose, applied a fine prism of rock-salt to Sir James South's great achromatic refractor. He found there was one defective band in the red space, and two or more in the blue space, so that the orange colour of the star arose from the greater defect of the blue than of the red rays. I
There can be little doubt that the predominance of yellow light in the heavens is due to the wide extension and powerful light-producing quality of sodium, especially as the spectra of Pollux, Capella, Betalgeus, and Procyon prove that this element exists in these stars. In Sirius and Castor we may assume that at least very little sodium exists. We shall be much interested to learn what elements produce the blood-red and the bluecoloured light of certain stars. What if we should be enabled to map out, however imperfectly, the whole of apparent space of the heavens into regions of the metals, regions of the alkalies, regions of the alkaline earths! How astounding if we should prove the existence of globes composed of little else than copper, silver, gold, or platinum, just as there is some reason for thinking that our own system is chiefly composed of iron! We may even discover elsewhere elements unknown in these parts of space. All the sciences have their own peculiar beauties and delights; but there is nothing which raises such intense wonder within us as astronomy in its descriptive and chemical branches. The wildest fables of the Arabian Nights Entertainments, so far from being foolish in their extravagance, will appear weak and commonplace for the very opposite reason, when we come to read such descriptions of the physical constitution of the sun and stars as may, before very long, be expected. Just at the present time, the scientific world is awaiting the publication, not only of further researches by Kirchhoff and Bunsen, but of the result of the Astronomer Royal's expedition to Spain at the late solar eclipse. Hence it is only common prudence to avoid mere speculation on these subjects.
* Ædes Hartwellianæ, p. 291. + Outlines of Astronomy, 4th ed., p. 580.
Prof. Swan appears recently to have made observations on this subject. In the Phil. Mag. [4), vol. ii. p. 448, he describes a method of measuring the planetary or stellar spectra by a prism and common sextant.
All discoveries concerning the spectrum have a very important bearing upon molecular philosophy. The definite rays in the spectrum of an element inform us most precisely of the vibrations of which the elementary atoms are capable. A complicated spectrum must indicate that the elementary atom is itself a compound of many simpler atoms; a suspicion of which fact has long been familiar to chemists, from the simple relation holding between the equivalent weights of several series of elements. Already some coincidences may be observed, which are probably more than accidental. Sodium, which has nearly the most simple spectrum possible, is likewise distinguished by the fact that all its salts are soluble, so that its determination by ordinary analysis is difficult. Again, iron, which has an extremely complicated spectrum, has the most extensive family relations with the other elements. At the present time, mathematicians, electricians, opticians, chemists, and even physiologists, are united in one immense confederation, irrespective of nation or of language, for the purpose of solving the great remaining problem of natural science,—that of the molecular constitution of matter, and the mutual relations of the physical forces. If we consider the intense concentration of the highest ability and the most unremitting labour upon this subject in every branch, which this century has witnessed for the first time in the history of mankind, we cannot think that the solution is far distant. The second great step in our knowledge of the world will then have been made, comparable in importance and difficulty to the discovery of the differential calculus and the law of universal gravitation, achieved, however, by a whole army of thinkers and workers, not by a single intellect.
ART. II.—THE EASTERN CHURCH: ITS PAST AND ITS
logy is "At an early ferent parties in the first Ref
Lectures on the History of the Eastern Church ; with an Introduc
tion on the Study of Ecclesiastical History. By Arthur Penrhyn Stanley, D.D., Regius Professor of Ecclesiastical History in the University of Oxford, and Canon of Christ Church. London,
Murray; Oxford, Parker. 1861. MARKED sympathy with the Eastern Church and Greek theology is no unprecedented phenomenon in our English Establishment. At an early period of our religious history predilection was expressed by different parties in a very decided way for the Latin or for the Greek Fathers. The first Reformers, and the great Puritan party, which inherited their principles, were strongly imbued with the spirit of Augustine's theology, and looked with comparative disfavour on the milder theories of Basil and Chrysostom. We are told that Bishop Cox, a high Calvinist, was sorely displeased at finding Queen Elizabeth one day intent on certain Greek Fathers. But reaction against Puritanism, and increasing devotion to Greek learning, -which had revived in Europe at the outbreak of the Reformation, and worked along with it as a powerful ingredient in the ensuing form of civilisation,-produced in England, before the close of the sixteenth century, an unequivocal transference of sympathy among the leading Churchmen from Augustine and his followers to the great doctors of the Eastern Church. Anglicanism was at once catholic and anti-papal. Repelled as strongly by the Puritans as by the Romanists, our Church sought relief to her unappeasable yearning in the spirit of a communion which was older than both. This tendency is traceable as early as Jewell.* It assumed a more rigid and authoritative tone, as the controversy deepened, in Andrewes and Laud. Its influence on Jeremy Taylor is unmistakable. The margin of his pages is filled with citations from the Greek preachers of the fourth century. When the Church was overthrown, the same theology, made dearer by contrast with the ascendant Calvinism, comforted the hearts of the dispossessed clergy under the enforced silence of their obscure retreats. The fruits of this were visible at the Restoration. From the first, the Liturgy had been enriched from Greek sources; and in the interval of persecution, the attachment of its adherents had strengthened for the old formularies, which expressed the devotion of the primitive Church before
* Apologia Eccles. Anglican. p. 29.