Louis XVIII. had entered his dominions towards the end of April, and received Alexander and Talleyrand at Compiègne. Pasquier confirms what has been alleged by many writers, that the Czar was treated with a kind of condescending pride, which disappointed and even galled him to the quick :

'He did not find in the King or in his family the cordiality and readiness to please which would have made his overtures simple and easy. He returned from Compiègne to Paris in a very different mood from that in which he had left to make his visit.'

Talleyrand, too, much as he had done to restore the throne, was graciously welcomed, but made to understand that the King trusted to his right, and had little faith in intrigues:

'The Restoration, in the eyes of the Royalists, was much more the work of necessity than of men. We had all said that to return to more legitimate principles was the only possible solution of the difficulties into which we had been thrown. . . . In the palace of the sovereign little gratitude could be hoped for, because we had taken the only course which could have saved us. Besides, when Talleyrand, one of the chief authors of the political revolution in favour of the House of Bourbon, came into its presence, he was associated with the most painful recollections, great as had been his services.'

The King, the Royal family, and the extreme Royalists had at this moment strong English sympathies, and this turned the Liberals and the partisans of Napoleon towards the Czar. The division of feeling became strongly marked, and, in view of events which have lately occurred, the following is curious, perhaps significant:

'The conflict between English and Russian influence caused a similar conflict between political parties in France. The Court and the émigré party ranged themselves on the side of England; those who had played an active and important part in recent events, and those who had been animated with hatred of the English in the wars of the Empire, took the side of Russia.'

Pasquier describes the reception of the Senate by Louis, and the arrangements by which he was placed on the throne, and bestowed the charter, made a sine quá non of his reigning, as an act of free grace to an obedient people. The entry of the King into Paris, like that of Monsieur, was hailed with an enthusiasm that knew no bounds, nor was this the mere levity of crowds of fickle citizens. The nation had escaped from a despotism of the sword; it had not yet realised all that it had lost; it looked forward to the Bourbons with hope; the worst ills of their régime had not yet

been felt; and it welcomed the advent of its ancient kings from across a gulf of troubled and destructive tempests:

'Even now the memory of that day affects me deeply. I recalled to mind the evil time when, with an afflicted heart, I gazed on the high walls of the Temple; I saw again the Place de la Révolution, the death of the King, the death of my father, and many hours when despair took possession of the bravest natures. Who, then, could have thought that that family, dispersed by the storm, would return in triumph, with the acclaim of the population of Paris?'

This volume only touches the first weeks of the government and administration of Louis XVIII. The faults committed by Monsieur were not amended; the King, though well meaning, and in some degree a statesman, was indolent, sickly, and let things drift, and he fell more and more into the hands of the émigrés. One of the changes he insisted on did immense mischief; he surrounded himself with a bodyguard of nobles, in imitation of the famous Maison du Roi, and relegated to obscurity the Guard of Napoleon, and this at a time when the army was full of discontent. The veterans of a hundred victories had not deserved this slight, even from the mere Royalist point of view; they had welcomed the King with respect when he had entered Paris. Pasquier sadly remarks, looking back at 1815:

'If, on the following day, a prince had told them, in the name of the King, "My friends, you are now the Royal Guard, the King and his family place themselves in your hands, and wish for no further pledge for their security than your courage and loyalty," these brave men would have been permanently won over.'

Pasquier protested to Dupont in vain on this subject:

'Have you not been informed what the Emperor said when leaving Fontainebleau ? "As for my Guard, if the King acts rightly, he will employ it, and will trust in it frankly; if he will not do this, he will have to disband it." You are bold enough to adopt neither course; you will place a formidable force of discontent at the head of the army. God grant that great evils may not follow!'

Pasquier became an object of the dislike of the Government, was removed soon afterwards from the direction of the police, and was made, what we should call, head of the Board of Works in France. This part of his reminiscences closes at this point, and we shall not anticipate succeeding volumes. The difficulties of the Bourbons were, no doubt, immense; but probably they were hardly greater than those surmounted by Henri IV. and Sully. Unfortunately, genius, judgement, and even good sense were wanting to France at this grave juncture, and the numberless errors of the restored monarchy were to lead to the Hundred Days and Waterloo.

ART. IV.-1. The Chemical Work of Faraday in relation to Modern Science. Lecture delivered at the Royal Institution, June 26, 1891. By Professor DEWAR, M.A., F.R.S. 2. Magnetic Properties of Liquid Oxygen. Lecture delivered at the Royal Institution, June 2, 1892. By Professor DEWAR, M.A., F.R.S.

3. Liquid Atmospheric Air.

Lecture delivered at the Royal Institution, January 20, 1893. By Professor DEWAR, M.A., F.R.S.

4. The Scientific Uses of Liquid Air. Lecture delivered at the Royal Institution, January 19, 1894. By Professor DEWAR, M.A., F.R.S.

THE

'HE 'third state' of matter was formally recognised by Van Helmont, a Belgian alchemist, early in the seventeenth century. But his discovery might have slipped back into oblivion had he not emphasised it by the invention of a name. The unseen and unfelt, yet material, substances brought into notice by his researches were called by him 'gases,' and are called so still. Atmospheric air was not included among them. For it ranked in those days as an 'element' in the Aristotelian sense. Boyle, however, became aware of its composite character, though he failed to isolate the vital' ingredient the existence and functions of which he divined. It was not, indeed, until more than a century later that oxygen was definitively captured by Priestley and Scheele. Carbonic acid, meanwhile, had been investigated by Black; Cavendish gave in 1766 the earliest description of inflammable air,' alias hydrogen; and nitrogen was made known by Priestley in 1772. Then Lavoisier, extricating these valuable discoveries from the misapprehensions in which they lay involved, and bringing them into logical connexion with the results of his own inquiries, shaped the new science of pneumatic chemistry.

Matter in general was thenceforward systematically studied under its solid, liquid, and gaseous forms. But there was as yet no certainty that every individual kind of matter was capable of assuming each in turn. One example of this versatility had, it is true, been at all times familiar. Water undergoes its cycle of changes from ice to steam naturally, and as a matter of common observation. No criterion was, however, at hand by which to decide whether, in so doing, it constituted an exception or followed a rule.

Indeed, we are still ignorant of any abstract principle bearing on the subject. Thus, apart from actual experience, there could be no well-grounded assurance that the behaviour of water would prove typical. Under altered conditions it even departs from its own standard. In a partial vacuum ice cannot be melted. When heated above freezing-point, in a vessel exhausted of air to a certain degree, it passes directly into vapour. On a planet, in fact, possessing an atmosphere 165 times rarer than our own, liquid water could not exist. Whether placed as near to the sun as Mercury, or as far from him as Neptune, such a globe could show neither seas nor streams. No rain could fall there, no dew be deposited; aqueous condensations should invariably take the form of snow. Sublunary experience, too, makes us acquainted with many complex substances which cannot change their state, because the application of heat very quickly tears their innermost structure to pieces. Who, for instance, would attempt to melt wood or leather? The very idea seems absurd, because every one knows that they char or burn while still solid. That is to say, they cease to be, as wood or leather, long before their respective ideal fusing-points are reached. Elementary bodies cannot, of course, be decomposed; but some resist liquefaction, if not absolutely, yet at least so far as to sublime without melting, like ice in a vacuum. One of these is arsenic. And carbon volatilises only at an enormously high temperature, and has never been liquefied. Possibly the intermediate state might be forced upon it by accompanying great heat with high pressure; but the idiosyncrasies of chemically distinct substances are so peculiar that its reluctance may represent real inability to liquefy.

The law, however, of the three states of matter is most probably universally valid both for simple bodies and for stable compounds. The power by which it is enforced resides in heat. Near the bottom of the scale of temperature, solidification reigns supreme; towards the opposite extreme, vaporisation. The moon exemplifies the first condition, the sun the second. Between the two stands our earth, in which solids, liquids, and gases co-exist. It is composed, in other words, of the three antique elements,' earth, water, and air. Now, the fact that, under the same circumstances, different substances are differently aggregated is none the less remarkable for being tritely familiar. It seems a matter of course that our atmosphere should, at all times and seasons, remain imperturbably ethereal—that

rigid rocks should enclose a heaving ocean, and that mercury, alone among metals, should flow like water. And it is easy to see that the prevalence of suchlike incongruities is essential to the scheme of things to which we ourselves belong. Unanimity among the various kinds of matter in freezing, melting, and boiling, would obviously exclude the possibility of life. The question, then, why it is excluded, answers itself; but if we go on to ask how it is excluded, we meet with no truly articulate response. All that can be said is that the observed wide diversities of melting and boiling points result from an equally wide diversity in the conditions affecting the molecular equilibrium of the substances severally concerned. As an explanation this is evidently unsatisfactory. It amounts to little more than a restatement of the same fact in different words. Yet the difference of wording is instructive it implies a good deal. Let us consider and draw out its meaning.

The word molecule '-equivalent to little mass-was employed in 1811 by an Italian physicist named Avogadro, to designate the smallest particles of any substance--solid, liquid, or gaseous-in which its distinctive qualities are preserved in their integrity. Molecules are not indivisible. They can be severed into atoms' by the influences of heat, light, electricity, or chemical affinity; but the operation is destructive of the body originally composed by them, and the new ones by which it is replaced are often wholly diverse from it in their qualities and relationships. Thus, each of the ultimate particles of water consists of at least three unimaginably minute portions-two of hydrogen and one of oxygen-the separation of which involves the demolition of water and the substitution for it of its gaseous constituents. Conversely, oxygen is converted into ozone when its molecules are compelled, through the action of electricity, to annex each a third atom of the stuff itself. Yet ozone, though nothing but oxygen chemically condensed, possesses highly characteristic qualities of its own.

Molecular structure, then, and the forces of which the modes of action are modified by it, determine the properties of matter. A molecule is a sub-microscopic piece of mechanism of exquisite flexibility, conjoined, in many cases, with a high degree of stability. An organic whole, complete in itself, it is nevertheless sensitive to manifold influences from without. It is all alive with energy in the shape of motion, the motive power being supplied by heat.

VOL. CLXXIX. NO, CCCLXVIII.

BB