ART. V.-MANUFACTURE OF SUGAR.*

HISTORY-CHRONOLOGICAL AND NATURAL OF THE SUGAR-CANE, AND OF SUGAR-AGENCIES OF HEAT, LIME, AND IMPURITIES.

In a practical treatise on the sugar manufacture, such as this is intended to be, any extended history, either chronological or natural, of the sugar-cane, and its crystalline product, would be out of place. On these subjects a few general remarks will suffice.

Of all eastern products, sugar appears to have been the latest known, out of the regions wherein it was produced. The chroniclers of ancient Egypt, Phoenicia, and India, make no mention of it; and it did not find its way into Arabia as a commercial article until the eleventh century soon after which, some adventurous Venetian travelers achieved the introduction of sugar as a commercial article into their metropolis. In Venice the first refineries were established; and hence the name, long prevalent, of pains de Venise as referring to loaves of sugar.

Even as regards the sugar-cane, the testimony of ancient authors is exceedingly devoid of precision. The most ancient writer by whom we find the sugar-cane recorded is Theophrastus, (B. C., 321,) who, in his chapter on honey, states as follows:-öri ai toù péditos yevégeis tpITTAí. ἢ ἀπὸ τῶν ἄνθων καὶ ἐν οἷς ἄλλοις ἐστιν ἡ γλυκύτης, ἄλλη δὲ ἐκ τοῦ ἀέρος, ὅταν ἀναχυθέν, ὑγρὸν ἀπὸ τοῦ ἡλίου συνεψηθὲν πέση, γίνεται δὲ τοῦτο μάλιστα ὑπὸ παραμητόν, ἄλλη δὲ ἐν τοῖς καλάμοις.Τ

"The generation of honey is threefold: the first is from flowers or other things in which there is sweetness; the second from the air, which, when there are dews, is concocted by the heat of the sun, and

* Continued from November number. The following notes were omitted in that number:

It will be seen, by reference to the formulæ given, that glucose is made up of the elements of (practical) cane sugar, plus the elements of three equivalents of water; hence a rationale is obtained of the facility with which the latter is changed into the former. Indeed, this conversion into glucose, which sugar experiences from slightly disturbing causes, is the first of a long series of destructive readjustments of elements to which sugar is subjected. Any approach to the boiling temperature of a solution of sugar instantly converts a portion of the latter into glucose; a change which is usually expedited by the presence of foreign matters in general, and by none more powerfully than alkalies and alkaline carths. This fact leads to a just appreciation of the great loss incurred by the present mode of colonial sugar manufacture.

I know not why glucose should be termed by some authors uncrystallizable. It crystallizes with great facility in slender needles, diverging from a centre, forming in the aggregate little masses of nodular or granular appearance. It certainly does not form hard crystals, and, in this respect, is very unlike canesugar. The term uncrystallizable sugar, as applied to it, is not only improper, but productive of confusion; that term having been applied by Proust, Ann. de Chim. Ivii. 131, to a sugar supposed to be liquid under all circumstances and uncrystallizable by any means, to be associated with both sugar of cane and glucose, and accounting, as he thought, for the existence of molasses and treacle.

† De Causis Plant., ed. Heinsii, 1613, p. 475.

falls, particularly in harvest time; the third sort is from canes or reeds."

Theophrastus, in another place,* mentions a sort of reed, or cane, growing in marshy localities in Egypt, and possessing sweet roots. The passage in question has been understood by some to refer to the sugar-cane; but there are many objections to the correctness of this assumption. The sugar-cane is not an aquatic plant, neither are its roots so sweet as its stem. Moreover, if it really had existed in Egypt, there were certainly those who would have chronicled the circumstance with more precision than we find in the above vague expression of Theophrastus.

If we are to rely upon the testimony of Strabo, in his history of India, written about the nineteenth year of the Christian era, Nearchus, the admiral of Alexander the Great, about 300 years before Christ, not only saw the sugar-cane in India, but was aware that a substance resembling honey (sugar) could be extracted from it. But, if the statement were true, the sugar-cane would seem to have remained very uncommon, and sugar still more so, seeing that Seneca and Lucan, who lived in the time of Nero, (A. D. 62,) adverted to the sugar-cane and to sugar in language so ambiguous and obscurethat some authorities have even doubted whether another plant and another substance might not have been intended. Seneca, in his 84th Epistle, has the following passage :—

"Aiunt inveniri apud Indos, mel in harundinarum foliis, quod aut ros illius cœli aut ipsius harundinis humor dulcis, et pignior gignat. In nostris quoque herbis, vim eandam, sed minus manifestam et notabilem, poni quam prosequatur et contrahat animal huic rei genitum." Lucan, treating of the Indians near the Ganges, writes:

Quique bibunt tenera dulces ab arundine succos."

After Seneca and Lucan, Pliny is the next author of repute who adverted to the sugar-cane. This was about the year 78, A. D. Subsequently to which period, and until the latter end of the dark ages, such little testimony as can be found relative to the sugar-cane and sugar is far too vague and unsatisfactory to merit attention.

To the crusades we probably are indebted for disseminating in Europe such a knowledge of the sugar-cane, and its crystallized product, as caused the speedy introduction of both into this quarter of the globe. The sturdy warriors of the cross, on their return to the west, began to desire many oriental luxuries for which they had acquired a taste. An oriental commerce was speedily established, and Venice became the great emporium of the riches of the east:-Of these, sugar was one.

Between the twelfth and fifteenth centuries the sugar-cane was cultivated in Sicily, the south of Spain, and indeed in many other Mediterranean regions. In the south of France, also, the culture of this plant was tried, but without success; the climate proving too uncer

* De Causis Plant., lib. vi. c. 16, ed. Heinsii.

tain, or too cold. In the Canary Isles, however, the cane culture was most productive, as was also the manufacture of sugar. These islands, in fact, continued to supply civilized Europe with the greater portion of her saccharine produce until the discovery of the West India Islands by the Spaniards, in 1492; and the maritime discovery of India by the Portuguese, opened newer and more congenial soils to the production of the tender crop.

Much controversy has existed on the question, whether the sugarcane were, or were not, indigenous to the new world. At the present epoch it would be impossible to determine this point, so much has the subject been involved by lapse of time and incapacity of the earlier historians. Fortunately the matter, so far as concerns practice, is of no importance whatsoever. Suffice it to know that the West India Islands, almost immediately subsequent to their discovery, began to supply civilized Europe with large quantities of sugar, and the less fertile fields of southern Europe soon fell into desuetude.

During a long series of years, the West India Islands produced sugar for the greater portion of the civilized world, and created large stores of wealth to the proprietors of their soil. At present, unfortunately, this condition of things exists no longer. The culture of the sugar-cane has now become extended over most tropical, and some temperate regions. To oriental nations, sugar-generally in its impure condition-is an article of daily food. The Chinese use it in profusion; so do the natives of Siam,-a country which, perhaps better than any other, is adapted to the successful produce of the sugar-cane. Throughout the whole of India, sugar is not only a common food for man, but immense quantities of the impure varieties of produce, called Jaggery,—are given to elephants. The amount of sugar capable of being produced by scientific processes of manufac ture, from the canes and the palm-tribe of India, may be so vastly increased, that it would be difficult to assign any limitation. The native processes of sugar extraction in India are so rude, and so destructive, that it may safely be asserted that 75 per cent. of the sugar existing in the juice operated upon is entirely destroyed in obtaining the re

mainder!

With regard to the natural history of the sugar-cane, very few remarks will suffice.

Botanists divide the vegetable world into phanerogamous or flowering, and cryptogamic or flowerless plants. With the latter we have

no concern.

Flowering plants are again divided into exogenous plants, or such as acquire increase of structure during growth by the deposition of external layers of tissue; and endogenous plants, or those which grow by depositions of tissue within the substance of their stem.

In temperate climes there are no large productions of the vegetable kingdom which belong to the endogenous class, all its representatives being of most humble growth. The grasses, for instance, are endogenous; and some of our larger grasses, as the wheat or barley, may be taken as the type of the endogenous vegetable produce in temperate regions.

It will be seen that there is no appearance of concentric rings, indicative each of a year's growth, but the whole cellular and vascular structure forms one confused mass.

For the purpose of fully appreciating the difference between an exogenous and an endogenous stem, the cane section may be compared with another of oak or hazel.

The difference between the two will be now marked; here the indications of peripheral depositions of tissue are so clear, each deposition corresponding with one summer, that, by counting the number of existing rings, the age of the exogenous plant may frequently be told. Besides the difference of the mode of growth between endogenous and exogenous grasses, a difference on which are founded the distinctive terms of botanical arrangement, there exist others no less invariable, and well marked. All exogenous plants are provided with reticulated leaves, whilst the leaves of all endogenous plants are merely traversed by straight veins; this distinction will be well sppreciated on making a comparison between an oak leaf and a leaf of barley or wheat.

Again, all exogenous plants possess a well-defined bark, wood, and pith; whilst in endogenous plants no such defined arrangement exists; -one part merging into the other by insensible gradations. Other distinctions between endogenous and exogenous plants there are, but they belong exclusively to the province of the botanist. If the stem of any of our larger grasses be examined, it will be found incrusted with a hard brilliant coating. This is no less than silica or flint, as may easily be demonstrated by various means. If, for example, a straw be dexterously acted upon by the flame of a blow-pipe,-the silica fusing with the potash naturally existing in all land vegetablesthere will result a beautifully transparent bead of glass. On a larger scale this production of glass from the same source is occasionally found amongst the debris of burnt hay or corn stacks. I have seen a lump of glass produced in this way, and weighing several pounds.

The sugar-cane is-botanically considered-a gigantic grass; and

the siliceous covering so sparingly developed in grasses of the temperate zone, here acquires so palpable a thickness, that small portions of such can easily be chipped off, either from the sugar-cane or the bamboo.

A horizontal, or transverse section, of the stem of the sugar-cane, if examined under the microscope, is seen to consist of a series of hexagonal cells in close juxtaposition. They are formed of a delicate tissue, which incloses them on all sides, in such a manner that each cell is altogether separated from the others to which it is contiguous. This structure is called the cellular structure, and is intermixed with another structure called the vascular, by which the nourishment for the plant's support is absorbed and circulated. (See cut, 628.)

Although it has been said that endogenous plants possess no defined bark, and the sugar-cane is no exception to the rule, yet this plant has a kind of pellicle, or rind; not separable, it is true, from the trunk, but indicated by its greenish color, which depends on a portion of the general coloring matter of leaves, to which chemists apply the denomination chlorophylle.

The arrangement of vessels and cells already described, as observed in a transverse section of the cane, will be still more fully comprehended by reference to a longitudinal section, a diagram of which is annexed. By reference to this diagram, which represents a longitudinal section of the cane at the point where a knot is formed, it will be seen that, in addition to the cellular structure already described, there is another structure-the vascular. The use of the latter is to minister to the circulation of the plant, hence the vessels contain the crude sap of the cane, which may be assumed to resemble very nearly the sap of plants in general, and which is, therefore, a very complex fluid: a circumstance very necessary to be borne in mind, as will hereafter be recognized.

With respect to the hexagonal cells,-microscopic experiments have demonstrated that they contain a fluid which is little else than pure sugar dissolved in pure water. The problems to be solved, therefore, are either to extract the matter of the cells alone, or to express all succulent matter from the canes, and afterwards to effect a separation between the sugar and its accompanying impurities. The first indication seems most philosophical, and it is one which a chemist in his laboratory would prefer to follow out. Taking advantage of the property which albuminous matters possess of coagulating on the application of heat, and remembering that such matters constitute the larger portion of the crude sap of the sugar-cane, the laboratory chemist would proceed by slicing his cane, drying the slices in a proper stove, and washing out the contained sugar by means of alcohol. Even without alcohol he could succeed in obtaining a good