if the Church held it to be right to give ecclesiastical supremacy to the see of Constantinople over the portion of the Roman Empire under her civil government, the same principle must justly apply to other countries similarly independent?

What has been the result of the refusal of Rome to accept that decision? From that time no General Council of the Universal Church has been held, nor can one be held so long as Rome claims and insists on its universal supremacy and the right of the Pope to accept or refuse any canon agreed to by such Council. Consequently those Councils on which Rome relies for her special doctrines have not been Councils of the whole Church, but only of the Church of Rome, and have not therefore proper Catholic authority. Monsignor Capel cannot show that the Council of Trent or the last at the Vatican were Councils of the whole Christian Church.

Is there not then reason for doubt in the Church of Rome on this account?

REDESDALE.

RECENT SCIENCE.

(PROFESSOR HUXLEY has kindly read, and aided the Compilers and the Editor with his advice upon, the following article.)

THE year 1774 will always stand out as a memorable year in the annals of chemical science. It was then that Priestley made his capital discovery of oxygen. It was then, too, that a poor Pomeranian apothecary, who had settled in Sweden, obtained for the first time a curious yellowish vapour, which was destined to acquire an importance almost equal to that of oxygen itself. This yellowish vapourthe Chlorine of modern chemists-was regarded, for many years, as a chemical compound; but from the time when Sir Humphry Davy brought forward the evidence upon which he based his opinion that it must be viewed as an undecomposable form of matter, chlorine has held its place, with but little dispute in this country, in our list of elementary gases.

It is therefore with much surprise that chemists have lately heard of certain experiments, conducted in the Zurich Polytechnikum, which tend to shake their faith in the views which have been accepted for well-nigh seventy years. We are asked, in fact, to believe that chlorine may, after all, turn out to be a compound body-possibly an oxygen-compound. Viewed in connection with other recent researches and speculations on the constitution of the so-called elements,' these experiments, and the deductions therefrom, are just now of peculiar interest; and, unless the Swiss chemists are curiously in error, their investigations will rank among the most important which have been undertaken during the past year.

To understand the strange reversion to old views which seems likely to follow from these recent researches, it is necessary to look back upon the history of chlorine. The discoverer of this gas was Carl Wilhelm Scheele, a native of Stralsund in Pomerania, who in 1773 removed to Upsala in Sweden. His taste for research had attracted the attention of the great chemist Bergmann; but the discoveries of the young apothecary soon overshadowed those of his patron, and gave rise to the remark that 'the greatest of Bergmann's discoveries was the discovery of Scheele.' 2

'See 'The Chemical Elements,' by J. Norman Lockyer. Nineteenth Century, Feb. 1879, p. 285.

The Chemical Essays of Charles William Scheele. London, 1786. Preface by Dr. Beddoes, of Edinburgh, p. vi.

It was during the examination of some ores of manganese that Scheele first procured chlorine. Although some of these ores had been known for ages, very crude notions prevailed as to their composition until Scheele entered upon their study. The most common ore of manganese is known to mineralogists as Pyrolusite, a name which it has received in consequence of its use by the glassmaker in cleansing, or decolorising, molten glass which may happen to have become tinted by the presence of iron. The same application of this 'fire-washing' mineral earned for it its old name of glass-soap;' and it is still known in French glass-houses as savon de verriers. Formerly it was called Magnesia vitrariorum or Magnesia nigra. But Scheele, in his elaborate investigation of the mineral, showed that it was distinct from the various substances with which it had previously been confounded, and that it represented, in short, a peculiar earth.3

In the course of his inquiry into the nature of this substance, Scheele subjected the manganese-ore to the action of various acids, including the spiritus salis. It was this experiment that led to the discovery of chlorine. When the manganese was digested in spirit of salt or marine acid, as it was also called in those days-Scheele observed an effervescence, due to the escape of a yellowish vapour which possessed a very pungent odour resembling that of warm aqua regia. This curious kind of air' he collected in a bladder which was tied to the neck of the vessel in which the manganese and acid were exposed to heat. He was thus enabled to examine the vapour, and especially to observe its powerful bleaching action upon vegetable colours a property which has since given to chlorine so much of its industrial importance.

The reaction which occurs during the preparation of the chlorine was interpreted by Scheele according to the lights of his day. At that time the famous phlogistic theory was flourishing, and Scheele explained the reaction by assuming that the manganese attracted phlogiston from the acid, while the residue was the suffocating yellow gas. This gas being therefore nothing but the marine acid deprived of its phlogiston, what more logical than to call it dephlogisticated marine acid? And such, in fact, was the name under which chlorine was originally introduced to the chemical world.

A careful inquiry into the nature of this gas led the French chemist, M. Berthollet, to take a different view of its constitution.1 Turning his back upon the phlogistic doctrine, he regarded the chlorine as a combination of the marine or muriatic acid with oxygen. Hence, when Lavoisier and his friends revised the chemical nomenclature of their day, they suggested the term 'gaz acide muriatique

Om Brun-sten eller Magnesia, och dess Egenskaper.' Kongl. Vetenskaps Academiens Handlingar, 1774, pp. 89-116.

Mémoire sur l'acide marin déphlogistiqué,' par M. Berthollet. l'Acad. Roy. des Sciences, année 1785, p. 276.

Mémoires de

oxygéné au lieu de gaz acide marin déphlogistiqué.'5 Even this new name soon took another shape when introduced into England, for Mr. Kirwan conveniently reduced the expression oxygenated muriatic acid to oxymuriatic acid. It was under this name that chlorine continued to be distinguished up to the time of Davy's classical researches.

Before referring to Davy's views on the elementary nature of chlorine, it should be mentioned that the two eminent French chemists, Gay-Lussac and Thénard, had suggested, prior to the publication of Davy's paper, the possibility of chlorine being a simple form of matter. Referring to the fact that this gas is not decomposed by carbon, they remark that 'on pourroit d'après ce fait et ceux qui sont rapportés dans ce mémoire, supposer que ce gaz est un corps simple.' Nevertheless they rejected such a supposition, and clung to the old belief in its compound nature, under the impression that it offered a more plausible explanation of the phenomena under discussion.

6

On November 15, 1810, Sir Humphry Davy read before the Royal Society the famous Bakerian lecture, in which he described the series of researches that led him to regard the yellowish vapour of Scheele as an elementary substance. In this discourse he shows that 'the body improperly called, in the modern nomenclature of chemistry, oxymuriatic acid gas, has not as yet been decompounded but that it is a peculiar substance, elementary as far as our knowledge extends, and analogous in many of its properties to oxygene gas.' It is worth noting, however, that he carefully avoids giving a direct denial to the statements of those who still held that the chlorine might be an oxygenated compound; for in taking exception to some experiments by Mr. Murray, of Edinburgh, he cautiousiy remarks, 'There may be oxygene in oxymuriatic gas, but I can find none.'

After Davy had given to the world his views on the chemical simplicity of chlorine, it took some time for them to gain general acceptance. Berzelius, for example, steadily resisted them for many years; and in France they were strongly opposed by Berthollet, though such men as Gay-Lussac and Thénard had become converts. In time, however, even Berthollet was converted; and, writing in 1816, he publicly expressed his concurrence in the generally accepted view. After referring to the fact that Gay-Lussac, Ampère, and Dulong had, for some years, taught in their lectures that chlorine

5 Méthode de Nomenclature chimique proposée par MM. de Morveau, Lavoisier, Berthollet et de Fourcroy.' Observations sur la Physique, juillet 1787, t, xxxi. p. 210.

De la nature et des propriétés de l'acide muriatique et de l'acide muriatique oxygéné.' Mémoires de Phys. et d. Ch. de la Soc. d'Arcueil, 1809, t. ii. p. 357.

On some of the Combinations of Oxymuriatic Gas and Oxygene, and on the Chemical Relations of these Principles to Inflammable Bodies.' Philosophical Transactions, 1811, p. 1.

was an element, he makes a remark which is worth quoting, since it exposes the jealousy between the French and English chemists of that day. Ils [Gay-Lussac and the others] ont bien droit à prétendre qu'ils ont les premiers regardé le chlore comme un être simple, quoique M. Davy ait le premier établi publiquement cette opinion, et sans connaître ce qui avait précédé.' 8

When Davy had convinced himself of the elementary nature of the so-called oxymuriatic acid, he naturally looked about for a more appropriate name. In his Bakerian lecture he tells us that, after consulting some of the most eminent chemical philosophers in this country, it has been judged most proper to suggest a name founded on one of its obvious and characteristic properties-its [greenish-yellow] colour-and to call it chlorine or chloric gas.'

The shock which has lately disturbed our faith in the soundness of Davy's views as to the elementary nature of chlorine has come from the researches of Professor Victor Meyer and Herr Carl Meyer, of Zurich, and is a direct consequence of their determination of the density of chlorine at high temperatures.

It is frequently required in chemical researches to ascertain the specific gravity of a substance when in the state of vapour, or, in other words, to determine its 'vapour-density.' Organic chemists especially have recourse to this operation in order to throw light upon the constitution of the various compounds which they prepare, and are therefore grateful for any means of simplifying the process. Some time ago Victor Meyer devised an ingenious method which is at once simple in principle and rapid in execution. It is by means of this new method that the density of chlorine at high temperatures was examined.

In Meyer's method, the specific gravity of the vapour is determined in a cylindrical glass vessel, to which is affixed an upright glass tube closed at the top with a caoutchouc stopper, and furnished at one side with a narrow delivery tube for the escape of air. The vessel may be raised to the required temperature by heating it in a bath of vapour or of liquid, having a proper boiling-point. If a very high temperature be required, as in the chlorine experiments, a gas furnace is used as a source of heat, and the bulb is constructed of porcelain. When the vapour-density of a solid or of a liquid is to be taken, the specific-gravity vessel is heated to the temperature necessary to volatilise the substance under examination. A weighed quantity of the substance is then cautiously introduced into the vessel, and the orifice at the top is immediately closed. The heat converts the body into vapour, and this vapour chases the air out of the vessel through the lateral delivery tube. The amount of extruded air is determined by collecting it in a graduated vessel standing over water,

Note sur la composition de l'acide oximuriatique.' Mémoires de la Soc. d'Arcueil, t. iii. p. 603. Memoir read April 10, 1816.