Marx, Capital, v.1:
The slave-owner buys his labourer as he buys his horse. If he loses his slave, he loses capital that can only be restored by new outlay in the slave-mart.___________________________________________________
But “the rice-grounds of Georgia, or the swamps of the Mississippi may be fatally injurious to the human constitution; but the waste of human life which the cultivation of these districts necessitates, is not so great that it cannot be repaired from the teeming preserves of Virginia and Kentucky. Considerations of economy, moreover, which, under a natural system, afford some security for humane treatment by identifying the master’s interest with the slave’s preservation, when once trading in slaves is practiced, become reasons for racking to the uttermost the toil of the slave; for, when his place can at once be supplied from foreign preserves, the duration of his life becomes a matter of less moment than its productiveness while it lasts. It is accordingly a maxim of slave management, in slave-importing countries, that the most effective economy is that which takes out of the human chattel in the shortest space of time the utmost amount of exertion it is capable of putting forth. It is in tropical culture, where annual profits often equal the whole capital of plantations, that negro life is most recklessly sacrificed. It is the agriculture of the West Indies, which has been for centuries prolific of fabulous wealth, that has engulfed millions of the African race. It is in Cuba, at this day, whose revenues are reckoned by millions, and whose planters are princes, that we see in the servile class, the coarsest fare, the most exhausting and unremitting toil, and even the absolute destruction of a portion of its numbers every year.”74
/Mutato nomine de te fabula narratur/ [It is of you that the story is told – Horace]. For slave-trade read labour-market, for Kentucky and Virginia, Ireland and the agricultural districts of England, Scotland, and Wales, for Africa, Germany. We heard how over-work thinned the ranks of the bakers in London. Nevertheless, the London labour-market is always over-stocked with German and other candidates for death in the bakeries. Pottery, as we saw, is one of the shortest-lived industries. Is there any want therefore of potters? Josiah Wedgwood, the inventor of modern pottery, himself originally a common workman, said in 1785 before the House of Commons that the whole trade employed from 15,000 to 20,000 people.75 In the year 1861 the population alone of the town centres of this industry in Great Britain numbered 101,302.
“The cotton trade has existed for ninety years.... It has existed for three generations of the English race, and I believe I may safely say that during that period it has destroyed nine generations of factory operatives.” 76
No doubt in certain epochs of feverish activity the labour-market shows significant gaps. In 1834, /e.g/. But then the manufacturers proposed to the Poor Law Commissioners that they should send the “surplus-population” of the agricultural districts to the north, with the explanation “that the manufacturers would absorb and use it up.” 77
Agents were appointed with the consent of the Poor Law Commissioners. ... An office was set up in Manchester, to which lists were sent of those workpeople in the agricultural districts wanting employment, and their names were registered in books. The manufacturers attended at these offices, and selected such persons as they chose; when they had selected such persons as their ‘wants required’, they gave instructions to have them forwarded to Manchester, and they were sent, ticketed like bales of goods, by canals, or with carriers, others tramping on the road, and many of them were found on the way lost and half-starved. This system had grown up unto a regular trade. This House will hardly believe it, but I tell them, that this traffic in human flesh was as well kept up, they were in effect as regularly sold to these [Manchester] manufacturers as slaves are sold to the cotton-grower in the United States.... In 1860, ‘the cotton trade was at its zenith.’ ... The manufacturers again found that they were short of hands.... They applied to the ‘flesh agents, as they are called. Those agents sent to the southern downs of England, to the pastures of Dorsetshire, to the glades of Devonshire, to the people tending kine in Wiltshire, but they sought in vain. The surplus-population was ‘absorbed.’”
74 Cairnes, “The Slave Power,” pp. 110. 111.
75 John Ward: “The Borough of Stoke-upon-Trent,” London, 1843, p. 42.
76 Ferrand’s Speech in the House of Commons, 27th April, 1863
77 Those were the very words used by the cotton manufacturers.” l.c.
For anyone who wants to read all these matters that Marx deals with in his Civil War dispatches and in Capital -- or if one doesn't trust Marx because, well, he's Marx! -- a more easily read work is by J.E. Cairnes M.A., Professor of Jurisprudence and Political Economy, Queen's College, Galway; and Late Whately Professor of Political Ecnomy at the University of Dublin. Cairnes, who most certainly is not Marx, is, in fact, a writer Marx quotes, including above. In this work Cairnes tries to explain to the English press in particular, how and why they have the American Civil War all wrong:
The Slave Power - Its - Character, Career, And Probable Designs - Being - An Attempt to Explain the Real Issues Involved in the American Contest (1862). Full text is available for viewing in google books and for pdf download.