and be capable of removal; or to add a known excess of lead salt to the sugar solution,-to separate the precipitate caused by filtration,— then to throw down from the filtered liquor all the remaining lead by means of some precipitating agent not productive of injury to sugar: and, as a subsidiary problem,-to remove the acetic acid liberated from the lead, either as an insoluble compound, or to combine it with some body that shall neither be injurious to sugar, nor to health, and separable, if possible, by the process of drainage.

Such are the necessities of the case,-even in the laboratory, on a small scale. Let us examine how they can be met.

The first problem does not admit of solution ;-it involves an impossibility: inasmuch as, however small, above a certain microscopic limit, the quantity of lead salt added,--the filtered solution will still contain lead: although a fresh addition of more lead salt to the filtrate will not fail to produce a new precipitate. This circumstance can be accounted for, by assuming the concurrent formation of two or more compounds of lead and vegetable matters; one compound being soluble, and the other not.

In operating on sugar thus, we are reduced to the necessity of disregarding, as a means of safety, all apportionment whatever:the only way left open to us is, to precipitate the excess of lead.

Simple as this may appear as a laboratory operation, it cannot be accomplished by the ordinary laboratory means. The usual agent employed by chemists to separate lead out of solutions is hydrosulphuric acid gas ;-a body which throws it down effectually from sugar solutions, it is true, but spoils the sugar:-in consequence of the facility with which, by trifling circumstances, it is decomposed, with the liberation of sulphur. Hence, so frequently had the experiment been tried, and with such uniformly bad success, that not only was the idea of employing these agents in combination relinquished, but the ruin of the sugar was attributed not to the proper causeviz: the effect of hydrosulphuric acid employed to separate the lead-but to the lead itself.

The employment of hydrosulphuric acid thus being out of the question, we have next to examine the other means commonly employed in the laboratory for accomplishing that end. Occasionally sulphuric acid is used to separate lead out of solutions; which end it accomplishes perfectly, even out of those of sugar; but if sulphuric acid be employed, it is incumbent on the operator to add one exact quantity no more--no less: if too much, the free or uncombined overplus of acid, by acting on the sugar, would speedily convert it-first, into glucose, and thence downward in the scale of destruction into glucic, melasinic, sacchulmic, sacchumic acids, &c. : if too little, there would remain an excess of lead; which not only is injurious to health, but, also, if boiled with sugar, a very destructive agent.

The question of lead, then, as a defecator for sugar, seemed hope

* Sulphuric acid has lately been tried by a gentleman in India, who utterly failed, however, in achieving the object proposed.

less. Its remarkable action was witnessed, admired, and abandoned; until in the year 1839, Messrs. Gwynne and Young took out a patent for the separation of the excess of lead by means of the diphosphate of lime ;--an agent which, in the laboratory, can be made to succeed perfectly; but which I believe to be, both on the score of expense and uncertainty, totally inapplicable on the large scale.

These gentlemen, however, deserve great praise for their investigations; which are, chemically considered, of a masterly kind. Although the operation necessarily failed in practice, for reasons which I have indicated, its perfect success in laboratory quantities demonstrated the most important fact, that the acetates of lead, per se, were not injurious to the constitution of sugar.

This demonstration having been accomplished, the chemist was warranted in resuming the task of finding out some precipitating body that should not only act in the laboratory under chemical superintendence; but one that should act anywhere, and in any quantity.

Such an agent I was fortunate enough to discover in July, 1847. This precipitant is sulphurous acid gas: the methods of employing which I have recorded in another publication, and therefore need not repeat here; seeing that my present object is simply to record a chemical fact.

Since the period of July, 1847, the efficacy of this gas has been tried on the large scale in a refinery, and also on cane juice; in both cases with the most perfect success.

ART. VI.-CHANCELLOR HARPER'S MEMOIR ON SLAVERY.*

Ir is worthy of remark, that there does not now exist on the face of the earth, a people in a tropical climate, or one approaching to it, where slavery does not exist, that is in a state of high civilization, or exhibits the energies which mark the progress towards it. Mexico and the South American republics, starting on their new career of

Continued from December Number.

The author of England and America thus speaks of the Columbian republic:

"During some years, this colony has been an independent state; but the people dispersed over these vast and fertile plains, have almost ceased to cultivate the good land at their disposal; they subsist principally, many of them entirely on the flesh of wild cattle; they have lost most of the arts of civilized life; not a few of them are in a state of deplorable misery; and if they should continue, as it seems probable they will, to retrograde as at present, the beautiful pampas of Buenos Ayres will soon be fit for another experiment in colonization. Slaves, black or yellow, would have cultivated those plains, would have kept together, would have been made to assist each other; would, by keeping together and assisting each other, have raised a surplus produce exchangeable in distant markets; would have kept their masters together for the sake of markets; would, by combination of labor, have preserved among their masters the arts and habits of civilized life." Yet this writer, the whole practical effect of whose work, whatever he may have thought or intended, is to show the ab

independence, and having gone through a farce of abolishing slavery, are rapidly degenerating, even from semi-barbarism. The only por tion of the South American continent which seems to be making any favorable progress, in spite of a weak and arbitrary civil government, is Brazil, in which slavery has been retained. Cuba, of the same race with the continental republics, is daily and rapidly advancing in industry and civilization; and this is owing exclusively to her slaves. St. Domingo is struck out of the map of civilized existence, and the British West Indies will shortly be so. On the other continent, Spain and Portugal are degenerate, and their rapid progress is downward. Their southern coast is infested by disease, arising from causes which industry might readily overcome, but that industry they will never exert. Grecce is still barbarous and scantily peopled. The work of an English physician distinguished by strong sense and power of observation*, gives a most affecting picture of the condition of Italy,especially south of the Apennines. With the decay of industry, the climate has degenerated towards the condition from which it was first rescued by the labor of slaves. There is poison in every man's veins, affecting the very springs of life, dulling or extinguishing, with the energies of the body, all energy of mind, and often exhibiting itself in the most appalling forms of disease. From year to year the pestilential atmosphere creeps forward, narrowing the circles within which it is possible to sustain human life. With disease and misery, industry still more rapidly decays, and if the process goes on, it seems that Italy too will soon be ready for another experiment in colonization.

Yet once it was not so, when Italy was possessed by the masters of slaves; when Rome contained her millions, and Italy was a garden; when their iron energies of body corresponded with the energies of mind, which made them conquerors in every climate and on every soil; rolled the tide of conquest, not as in later times, from the South to the North; extended their laws and their civilization, and created them lords of the earth.

"What conflux issuing forth or entering in;
Prætors, pro-consuls to their provinces,
Hasting, or on return in robes of state.
Lictors and rods, the ensigns of their power,
Legions and cohorts, turms of horse and wings :
Or embassies from regions far remote,

In various habits, on the Appian road,

Or on th' Emilian; some from farthest South,
Syene, and where the shadow both way falls,
Meroe, Nilotic isle, and more to West,

The realms of Bocchus to the Blackmoor sea;
From th' Asian kings, and Parthian among these;

solute necessity, and immense benefits of slavery, finds it necessary to add, I suppose, in deference to the general sentiment of his countrymen, "that slavery might have done all this, seems not more plain, than that so much good would have been bought too dear, if its price had been slavery." Well may we say that the word makes men mad.

* Johnson on Change of Air.

From India and the golden Chersonese,
And utmost India's isle, Taprobona,

Dusk faces, with white silken turbans wreathed;
From Gallia, Gades and the British West;
Germans and Scythians, and Sarmartians, North
Beyond Danubius to the Tauric Pool!

All nations now to Rome obedience pay."

Such was and such is the picture of Italy. Greece presents a contrast not less striking. What is the cause of the great change? Many causes, no doubt, have occurred; but though

"War, famine, pestilence and flood and fire

Have dealt upon the seven-hilled city's pride,"

I will venture to say that nothing has dealt upon it more heavily than the loss of domestic slavery. Is not this evident? If they had slaves, with an energetic civil government, would the deadly miasma be permitted to overspread the Campagna and invade Rome herself? Would not the soil be cultivated, and the wastes reclaimed? A late traveller mentions a canal, cut for miles through rock and mountain, for the purpose of carrying off the waters of the lake of Celeno, on which thirty thousand Roman slaves were employed for eleven years, and which remains almost perfect to the present day. This, the gov ernment of Naples was ten years in repairing with an hundred workmen. The imperishable works of Rome which remain to the present day were, for the most part, executed by slaves. How different would be the condition of Naples, if for her wretched lazaroni were substituted negro slaves, employed in rendering productive the plains whose fertility now serves only to infect the air!

To us, on whom this institution is fastened, and who could not shake it off, even if we desired to do so, the great republics of antiquity offer instruction of inestimable value. They teach us that slavery is compatible with the freedom, stability and long duration of civil government, with denseness of population, great power, and the highest civilization. And in what respect does this modern Europe, which claims to give opinions to the world, so far excel themnotwithstanding the immense advantages of the Christian religion and the discovery of the art of printing? They are not more free, nor have performed more glorious actions, nor displayed more exalted virtue. In the higher department of intellect-in all that relates to taste and imagination-they will hardly venture to claim equality. Where they have gone beyond them in the results of mechanical philosophy, or discoveries which contribute to the wants and enjoyments of physical life, they have done so by the help of means with which they were furnished by the Grecian mind-the mother of civilization and only pursued a little farther the track which that had always pointed out. In the development of intellectual power,

* Eight days in the Abruzzi.-Blackwood's Magazine, November, 1835. 4

VOL. II.

they will hardly bear comparison. Those noble republics, in the pride of their strength and greatness, may have anticipated for themselves—as some of their poets did for them-an everlasting duration and predominance. But they could not have anticipated, that when they had fallen under barbarous arms, that when arts and civilization were lost, and the whole earth in darkness-the first light should break from their tombs-that in a renewed world, unconnected with them by ties of locality, language or descent, they should still be held the models of all that is profound in science, or elegant in literature, or all that is great in character, or elevated in imagination. And perhaps when England herself, who now leads the war with which we are on all sides threatened, shall have fulfilled their mission, and like the other glorious things of the earth, shall have passed away; when she shall have diffused her noble race and noble language, her laws, her literature and her civilization, over all quarters of the earth, and shall perhaps be overrun by some Northern horde-sunk into an ignoble and anarchical democracy,* or subdued to the dominion of some Cæsar,-demagogue and despot,-there, in Southern regions, there may be found many republics, triumphing in Grecian arts and civilization, and worthy of British descent and Roman institutions.

If after a time, when the mind and almost the memory of the republic were lost, Romans degenerated, they furnish conclusive evidence that this was owing not to their domestic, but to their political slavery. The same thing is observed over all the eastern monarchies; and so it must be, wherever property is insecure, and it is dangerous for a man to raise himself to such eminence by intellectual or moral excellence, as would give him influence over his society. So it is in Egypt and the other regions bordering the Mediterranean, which once comprehended the civilization of the world, where Carthage, Tyre and Phoenicia flourished. In short, the uncontradicted experience of the world is, that in Southern States where good government and prædial and domestic slavery are found, there are prosperity and greatness; where either of these conditions is wanting, degeneracy and barbarism. The former, however, is equally essential in all climates and under all institutions. And can we suppose it to be the design of the Creator, that these regions, constituting half of the earth's surface, and the more fertile half and more capable of sustaining life, should be abandoned forever to depopulation and barbarism? Certain it is, that they will never be reclaimed by the labor of freeIn our own country, look at the lower valley of the Mississippi, which is capable of being made a far greater Egypt. In our own state, there are extensive tracts of the most fertile soil, which are capable of being made to swarm with life. These are at present pestiTential swamps, and valueless, because there is abundance of other fertile soil in more favorable situations, which demand all and more than

men.

*I do not use the word democracy in the Athenian sense, but to describe the government in which the slave and his master have an equal voice in public affairs.