acid, in the form of sulphate of ammonia, leaving oxide of copper and oxide of iron, the former of which is easily reduced to a metallic state. The roasted ore is then mixed with 200 grains of carbonate of soda, 20 grains of carbon or lamp-black, and 20 grains of lime, introduced into the same crucible and covered with 20 grains of borax, and smelted in the assay furnace until the whole mass becomes perfectly liquid, when it may be withdrawn from the fire and allowed to cool; the crucible is then broken, and a button of copper will be found at the bottom. The small piece of metal obtained by this fusion must be beaten under the hammer, and if it is perfectly malleable, without cracking at the edges, the button may be considered as fine or pure copper; if not, it has to be refined by repeatedly fusing it with about 20 grains of a mixture of carbonate of soda, nitre, and common salt, until the metal becomes perfectly malleable.

All kinds of copper ores cannot be assayed by this method. The mode of treatment varies according to the composition of the ore, and as copper pyrites is the ore which comes chiefly under our notice, I have thought it sufficient to describe the mode of assaying this mineral. The dry assay yields the amount of copper which the smelter obtains on the large scale; but if he wish to know the exact quantity of copper that the ore contains, we must have recourse to the humid assay. The following methods are those generally used for this purpose:

Copper is generally determined as an oxide by precipitation with a fixed caustic alkali. For this purpose the ore is dissolved in a mixture of nitric and hydrochloric acids until nothing but a siliceous matter is left; if any other metals but iron are present, they must be separated according to the routine of chymical analysis; if the latter metal, however, is the only one present, it is only necessary to dilute the solution and add ammonia in excess, which precipitates the iron, the copper being held in the solution, which, as we have already observed, has a beautiful blue colour. The iron is separated by filtration and the filtrate boiled; as soon as the liquor has reached the boiling point, a solution of caustic potash, or caustic soda, is added to it, the blue colour disappears, and the whole of the copper will be precipitated in the form of an oxide, if the experiment be conducted successfully. The precipitate is thrown upon a filter, carefully washed, dried, and ignited in a platinum crucible; from the amount of oxide of copper obtained, the amount of metallic copper is calculated, forty grains of oxide being equivalent to thirty-two grains of copper. If the ore be rich, fifty grains will be found sufficient to analyze; if it be poor, it will be found necessary to use one or two hundred grains. There are several other methods of determining the amount of copper in an ore,

aud I shall conclude by describing two of them, as they are the processes generally adopted, being much shorter than the one already described. An assay by either of them may be conducted in about half-an-hour.

Great attention has lately been paid to the rapid determination of copper by means of standard solutions, and we are indebted to Messrs. Pellouze and Parkes for these valuable methods.

Pellouze's process depends upon the decolorization of an ammoniacal solution of copper, by means of sulphuret of sodium of a known strength. To determine the strength of this solution, a given quantity is dissolved in water, and about twenty grains of pure copper are dissolved in acid, to which ammonia is added in excess. The liquor is boiled in a flask, and the solution of sulphide of sodium is gradually added thereto, from a burette (a graduated measure divided into a hundred equal parts), until the solution becomes colourless, and no more precipitate is formed. We obtain by this means a solution of a known strength; e.g., supposing we have used fifty measures, by a simple proportion we find that every measure corresponds to 0.4 grains of pure copper.

To determine the amount of copper then in an ore, if no other metal be present but iron, we adopt the method already described for separating it, add the sulphuret of sodium until no more precipitate is formed, and multiply the number of divisions used by 0.4, being the amount of copper to which each measure corresponds.

Parke's process is even more easily conducted than that of Pellouze, as the ammoniacal solution of copper does not require boiling, and depends upon its decolorization by means of cyanide of potassium. In this instance no precipitate is formed, but a change of colour takes place. The graduated or standard solution of cyanide of potassium is prepared in exactly the same manner as the sulphuret of sodium, by dissolving a quantity in water, and observing how many measures are required to decolorize twenty grains of pure copper; and employing the same process (upon fifty or a hundred grains of the ore,) after the iron has been separated. The cyanide of potassium used must be perfectly pure, and free from ferrocyanide or sulphide of potassium, as both these substances are exceedingly detrimental, and would completely vitiate the results obtained

EIGHTH ORDINARY MEETING,

Held at the ROYAL INSTITUTION, on the 9th February, 1857,

THOMAS INMAN, Esq., M.D., PRESIDENT, in the Chair.

The resignation of Mr. Alfred Holt was received.

The SECRETARY intimated that the following address had been forwarded to the Rev. Dr. Livingstone:-

TO THE REV. DR. LIVINGSTONE, &c., &c., &c.

SIR,-The members of the Literary and Philosophical Society of Liverpool desire to express to you the gratification which they have felt in hearing of those great geographical discoveries which you have made in Africa.

While seeking to spread the priceless blessings of Christianity in an unknown, unexplored country, you have opened up a new and most important territory. Alone in this vast enterprise, you have been permitted to complete your discoveries, and to return home to receive the congratulations and the honours which have been extended towards you.

The members of this Society, with others of your countrymen, hailed the news of your having found the waters of the Ngami, and were encouraged therefrom to expect further discoveries. They have, therefore, the highest satisfaction in knowing that from Linyanti, in the interior of that great continent, you have been enabled to trace the flowing of the Zambesi to the Indian ocean, and thus to associate your name with a discovery which, viewed either in the light of science, philanthropy, or commerce, is of incalculable importance.

If you should again travel in that quarter of the world, the members will watch your course with the deepest interest; and hope, not only that much success may attend you, but that you may be spared to return in perfect health and safety.

THOMAS INMAN, M.D., PRESIDENT. Extracted from the minutes of the Literary and Philosophical Society of Liverpool.

BY WILLIAM IHNE, Esq., PH.D., V.P.

The republican form of government, as known to the ancients, was entirely municipal. All the illustrious republics of Greece were free towns, governing themselves, and ruling over a small suburban district.

The representative principle, by which such a government might expand over large countries without becoming despotic, was as foreign to the political wisdom of antiquity as the conception of a social condition without slavery. Hence the impossibility of forming a comprehensive Greek state. Athens no sooner became pre-eminent and dominant, than she became despotic. No means were found to establish an equality of rights between the people of the annexed territories and of Athens. There was no free alliance and equal union for the formation of a large commonwealth of freemen. Power and liberty resided only in one centre. Those who were at a distance from that centre, had only the choice between subjection and perfect separation. The small Greek cities had too much of local life and vigour to submit for any length of time to the former, and none of them had a territory sufficiently ample, or political wisdom and martial strength enough, to rise permanently to uncontested superiority, and to enforce obedience.

But the

The first

Rome was more wise, determined, or fortunate. The inhabitants of this one city became the rulers first of a densely peopled district all round the political centre, and then of the whole of Italy. This was already a severe test of the permanence of their municipal government. Yet their fortune carried them vastly beyond even these limits, and in course of time they became the masters of the world. glory of conquest was purchased with the loss of freedom. general, who led a Roman army beyond the sea, was no longer merely a servant of the citizens of Rome-he was a member of the ruling aristocracy, destined to become more powerful, more arrogant, more selfish and rapacious, in proportion as the legions added more and ever more provinces to the huge dominion of the Empire City. During the period of his command he swayed monarchical power, and it was found impossible to bring him back again to the modest position of a private citizen.

A great anomaly was thus created. The state was brought into a strange, unnatural condition, which could not last long. The populace of an overgrown town-poor, idle, abject, and venal-pretended to govern a vast empire. The elections and laws, made in the Roman forum by a turbulent and ignorant mob, determined. the fate of the once free and flourishing commonwealths of Greece and Asia, of the dwellers on the Ebro, the Rhone, the Po, the Hebrus. But this popular sovereignty was all sham and illusion. The real governors of the Roman world were behind the scenes, and pulled the strings. It was the aristocracy, who brought the people to the forum to give their votes and to confer armies and provincial governments on the members of the noble houses. In the unfortunate provinces these

L

men amassed the wealth necessary to pay the venal crowds of the forum. It was of no use, that a court of justice was established in Rome to inquire into and punish these habitual acts of robbery. The chief consequence was, that more extortion became necessary, to enable the offenders to buy off the judges too.

This state of things carried in itself the elements of its dissolution. The examples of wealth, influence, and power, iniquitously obtained at the expense of the community, through the machinery of the old constitution could not fail to stimulate every successive generation of nobles to ever increased ambition and recklessness. The greater the ability of these men, the vaster became their influence-the more threatening their position, the smaller became their number, until it was reduced by degrees to three, to two, and at last to one. Monarchy was thus the natural and inevitable result of the subjection of an empire under the government of a city.

That this change was not only natural and inevitable, but also salutary to the interests of mankind, is proved by the ease, with which, when once established, it was maintained. The only losers were the aristocracy and the populace of Rome; among them alone we find the sources of discontent and the disposition to rebel. The provinces at once felt the beneficial effect of monarchical government. Formerly they had been governed only to be taxed. Now they were taxed to be governed. No military force therefore was necessary to keep them in subjection; the army was stationed along the frontiers to defend the empire from the barbarians; and even in Italy and in Rome the number of troops was wonderfully small in comparison with what we are accustomed to consider necessary to ensure the stability of most governments.

This fundamental change in the government of the Roman Empire was effected by Augustus without a corresponding change in the traditional forms and names. He preserved not only the old officers of state with their old names, attributes, and functions, not only the venerable institution of the senate, the real seat and centre of the life of the republic, but even the popular assemblies, though they might seem to contain an element hostile to his own sovereign power. The task of Tiberius was thus much simplified and facilitated. He had merely to follow up the wise principles established by Augustus, and he did so with much tact and firmness. Things were indeed, as yet, far from having settled down into an established order and generally acknowledged rule. There were still many alive, who remembered the days, when liberty was the watchword of the aristocratic party. (Tac. Annal Tiberius was still the first of his race, and had not yet