most northern countries, cane sugar is only an article of luxury, though one with which many would now find it difficult to dispense. In many tropical regions, however, the sugar cane forms a staple part of the ordinary food. The ripe stalk of the plant is chewed and sucked after being made soft by boring it, and almost incredible quantities are consumed in this way. Large ship-loads of raw sugar cane are daily brought to the markets of Manilla and Rio Janeiro; and it is plentiful in the market of New Orleans. In the Sandwich and many other islands of the Pacific, every child has a piece of sugar cane in its hand; while in our own sugar colonies the negroes become fat in crop time on the abundant juice of the ripening cane. This mode of using the cane is, no doubt, the most ancient of all, and was well known to the Roman writers. Lucan (book iii. 237) speaks of the eaters of the cane as

"Quique bibunt tenerâ dulees ab arundine succos."

"And those who drink sweet juices from the tender reed."

This nutritive property of the raw juice of the sugar cane arises from the circumstance that it contains, besides the sugar to which its sweetness is owing, a considerable proportion of gluten, as well as of those necessary mineral substances which are present in all our staple forms of vegetable food. It is thus itself a true food,* capable of sustaining animal life and strength without the addition of other forms of nourishment. This is not the case with the sugar of commerce, which, though it in a certain sense helps to nourish us, is unable of itself to sustain animal life.

The juice of the sugar cane varies in composition and richness with the variety of cane, the nature of the soil, the mode of cultivation, and the dryness of the season.

Sce THE BREAD WE EAT.

Its

:

COMPOSITION OF THE SUGAR CANE.

207

average composition in sugar plantations, when the canes are fully ripe, is about

The richness in sugar varies with many circumstances, and especially with what is called the ripeness of the cane. For it is a curious circumstance in the chemical history of this plant that the sap sweetens only to a certain distance up the stem; the upper somewhat green part, which is still growing, yielding abundance of sap, but comparatively little sugar. One reason of this probably is, that as fast as the sugar ascends with the sap, it is converted into woody matter, which is built in to the substance of the growing stem and leaves. In consequence of this want of sweetness, the upper part of the cane is cut off, and only the under ripe part employed in the manufacture of sugar. In Louisiana, where the canes rarely ripen so completely as in the West Indies, the proportion of sugar contained in the juice is set down as low as 12 to 14 per cent."

For the extraction of the sugar, the canes are cut with a large knife, the labourer proceeding between the rows (fig. 38). The leaves and tops are then chopped off and left in field, while the under ripe part is carried to the mill. These ripe canes are passed between heavy iron crushing-rollers, which squeeze out the juice. This juice is run into large. vessels, where it is clarified by the addition of lime and other applications. The action of this lime is twofold. It removes or neutralises the acid which rapidly forms in the fresh juice, and at the same time combines with the gluten

Patent Office Report, 1844.

of the juice, and carries it to the bottom. This gluten acts as a natural ferment, causing the sugar to run to acid. Its

Fig. 88.

speedy removal, therefore, is essential to the extraction of the sugar. After being clarified in this way, and sometimes filtered, the juice is boiled rapidly down, is then run into wooden vessels to cool and crystallise, and, finally, when crystallised, is put into perforated casks to drain. What remains in these casks is Muscovado or raw sugar; the drainings are well known by the name of molasses. Simple as this process is in description, it is attended with

many difficulties in practice. It is diffi

cult to sqeeze the whole of the juice out of the cane-it is difficult to clarify the juice with sufficient rapidity to prevent it from fermenting, and so completely as to render skimming unnecessary during the boiling-it is difficult to boil it down. rapidly without burning or blackening, and thus producing much uncrystallisable molasses-and it is difficult afterwards to collect and profitably employ the whole of the molasses thus produced. The difficulties, though none of them insurmountable, have hitherto proved so formidable in practice,

DIFFICULTIES IN THE MANUFACTURE.

209

that, of the 18 per cent. of sugar contained in the average cane juice of our West India Islands, not more than 6 per cent., or one-third of the whole, is usually sent to market in the state of crystallised sugar! The great loss which thus. appears to take place is thus accounted for

First, Of the 90 per cent. of sweet juice which the cane contains, only 50 to 60 per cent. are usually expressed. Thus one-third of the sugar is left in the megass, or squeezed cane, which is used for fuel-(KERR.)

Second,-Of the sugar in the juice, one-fifth or more is lost by imperfect clarifying, and in the skimmings removed during the boiling-(SHEIR.)

Third, Then of the juice when boiled down to the crystallising point and set to cool, only from one-half to twothirds crystallises: the rest drains off as molasses. Thus of the whole sugar of the ripe cane

The molasses and skimmings are fermented and distilled for rum. But even of the molasses much is lost, the drainage from the raw sugar of the West Indies, while at sea, is stated at 15 per cent., and afterwards, in the docks, at 2 per cent. And further, the leakage of the molasses itself, which is shipped as such, is 20 per cent.; so that of the ununcystallisable part of the sugar, also, there is a large waste. In the interior of Java, where fuel is scarce, the molasses is worthless, and is sent down the rivers in large quantities; but in the West Indies it has everywhere a market value, and may be distilled with a profit.

The sugar manufacture, therefore, of our West India

colonies, appears as a whole to be in a most unsatisfactory condition. Neither mechanical nor chemical means have been applied to it as they have been to the sugar manufacture of Europe; and it is not at all surprising that pecuniary difficulties should of late years have gathered round the unimproving planters. The same skill which now extracts 7 per cent. of refined sugar from the more difficult beet, might easily extract 10 or 12 from the sugar cane. Were this result generally attained, the same weight of canes which is now grown in the West Indies, and which yields less than half the quantity of crystallised sugar actually consumed in the United Kingdom, would alone produce enough to supply the entire present home consumption.

The means by which this better result is to be attained are, the use of improved crushing rollers, by which 70 and even 75 per cent. of juice can be forced from the canes-of better modes of clarifying, which chemical research has recently discovered-of charcoal filters before boiling, which render skimming unnecessary-of steam and vacuum boilers, by which burning is prevented, and rapid concentration effected-of centrifugal drainers to dry the sugar speedily and save the molasses-and of coal or wood as fuel where the crushed cane is insufficient for the purpose. By the use of such improvements, planters in Java, in Cuba, and, I believe, here and there in our own colonies, are now extracting and sending to market 10 to 12 per cent. of raw sugar from the 100 lb. of canes! Why should our own enterprising West India proprietors spend their time in vain regrets and longings for the past, instead of earnestly availing themselves of those scientific means of bettering themselves which are waiting to be employed, and which are ready to develop themselves to meet every new emergency? It is not the readier or cheaper supply of labour which gives the Dutch planter of Java, or the Spanish planter of Cuba, 10 per cent. of