This section is from the book "An Experimental History Of The Materia Medica", by William Lewis.
Sugar: a sweet substance, of a saline nature; prepared from the juice of an elegant large cane or reed, arundo saccharifera C. B. which grows spontaneously in the East Indies and some of the warmer parts of the Weft, and is cultivated in large plantations in several of the American islands. The expressed juice of the cane is clarified with the addition of lime water, and boiled down to a somewhat thick consistence: being then removed from the fire, the saccharine part concretes into brown coloured maffes, saccharum non purificatum Pharm, Lond. leaving an unctuous liquid matter called melaffes or treacle, from which a little more solid sugar, but of a coarser kind, is obtainable by a repetition of the boiling and clarification. The brown sugar is purified in conical moulds, by spreading, on the upper broad surface, - some moist clay; whose watery moisture, slowly per colating through the mass, carries with it a considerable part of the remains of the treacly matter. The clayed sugar, imported from America, is by our refiners dissolved in water, the solution clarified with whites of eggs, and after due instillation, poured as before into conical moulds, where, as soon as the sugar has concreted, and the fluid part is drained off by an aperture at the bottom, the surface of the loaf is again covered with moist clay. The sugar, thus once refined, saccharum album becomes, by a repetition of the process, the double-refined sugar of the shops, saccharum puriffimum Pharm. Lond. & Edinb. Solutions of the brown or white sugars, boiled down till they begin to grow thick, and then removed into a very hot room, shoot, upon sticks placed across the vessels for that purpose, into brown or white crystals or candy, saccharum crystal-linum.
(a) Med. Eff. Edinb. III. 395.
Sugar dissolves by the assistance of heat, in rectified spirit; but greatest part of it separates again in the cold, and concretes into a crystalline form: on this foundation, saccharine concretions are obtained from saturated spirituous tinctures of several of the sweet plants of our own growth; the saccharine part separating when the tincture is set in the cold, while the resinous or other matter extracted from the plant, remains dissolved in the spirit. Solutions of sugar mingle uniformly with those of other saline substances, whether acid, alkaline, or neutral; and make no visible alteration in the infusions of the coloured flowers of vegetables, or other liquors, in which acids or alkalies produce a change of colour or a precipitation. This sweet saline substance appears on all trials completely neutral*(a) and unites with mod kinds of humid bodies, without altering their native qualities: it serves as an intermedium for uniting together some bodies naturally repugnant, as distilled oils and water. On the same principle it impedes the coagulation of milk, and the se-paration of its butyraceous part.
Sugar, in consequence of this property, is supposed to unite the unctuous part of the food with the animal juices. Hence some have concluded, that it increases corpulence or fatness; others, that it has a contrary effect, by preventing the separation of the oily matter, which forms fat, from the blood; and others, that it renders the juices thicker and more fluggish, retards the circulation, obstructs the natural secre-tions, and thus occasions or aggravates scorbu-tic, cachectic, hypochondriacal and other disor-ders. General experience, however, has not shewn, that sugar produces any of these effects in any remarkable degree: its moderate use appears to be innocent; and perhaps, of all that have yet been discovered, it is the mod univer-sally innocent and inoffensive, as well as the most simple, sweet.
Sugar preserves both animal and vegetable substances from putrefaction, and appears to possess this power in a higher degree than the common alimentary salt: I have seen animal flesh preserved by it untainted for upwards of three years. From this property it has been sometimes applied externally as a balsamic and antiseptic.
* (a) An acid of a peculiar kind has been separated from it in small proportion and by a laborious process, in which the nitrous acid is employed as the separatmg medium.
The impure brown sugars, by virtue of their oily or treacly matter, prove emollient* and gently laxative. The crystals or candy are most difficult of solution, and hence are pro-perest where this soft lubricating sweet is wanted to dissolve slowly in the mouth, as in tickling coughs and hoarseness. The uses of sugar in medicinal compositions, whether for their pre-servation, for procuring the intended form and consistence, or for reconciling to the stomach and palate substances of themselves disgustful, are too obvious to require being enlarged on.