The principle called glycyrrhizin, obtained from the liquorice-plants, and the analogous principle from the leaves of the abrus precatorius, and the root of the common polypody fern, probably belong here, as well as sarcocollin, which exists both in Pen ee& mueronata, P. Sarco collet, and in the polypody. Picromel, or the sweet principle which exists in the bile of mammals and birds, is probably a variety of sugar, though =susceptible of fermentation, and ought to be considered in conjunction with it, from the share it may have in augmenting the sugar in diabetes. (Sce Experiments of Claude Bernard.) In treating of the dietetical properties of sugar, it is necessary to view it in a variety of conditions. In temperate climates sugar is regarded as a luxury, one indeed which is nearly indispensable ; but in tropical countries it is a universal article of subsistence, partly as real sugar, and partly, and more generally, as it occurs in the cane, which is either simply chewed or sucked, or softened by previous boiling. In this state it is eminently nutritious. It has been called "the most perfect alimentary substance in nature," and the results, in the appearance of the ncgroes, during the cane harvest, notwithstanding the increased severe toils of that season, seem to confirm the statement. They almost invariably become plump and sleek, and scarcely take any other food while the harvest lasts ; even the sickly revive, and often recover their health. The crude plant, or the newly expressed juice, contains water, sugar, gum, green fecula, extractive, gluten, acetic and malic acids, acetates of lime and potash, eupermalate and sulphate of lime, and lignin. It is the object of the various processes to which the juice is subjected, both in the countries where it is produced and where it is refined, to separate the sugar from the other ingredients, some of which dispose it to ferment and spoil, and others are obstacles to its crystallising. (See a valuable paper by Messrs. Guynne and Young, British Annals of Medicine,' vol. i., p. 778; and ii., p. 42, where they enumerate tannic acid and oxide of iron among the ingre dients of raw sugar). By the removal of such of these principles as contain azote, especially the gluten and green fecula, the nutritive power of sugar is sensibly diminished.
However harmless the use of saccharine vegetables may be to per sons in health, there cannot he a doubt but that in some instances they are extremely hurtful. " The derangement or partial suspension of the converting the saccharine principle in man into the albuminous or oleaginous, not only constitutes a formidable species of dyspepsia, but the unassimilated saccharine matter in passing through the kidneys gives occasion to the disease termed diabetes." The blood of a perfectly healthy individual contains no appreciable quantity of sugar ; but in diabetes, sugar has been repeatedly ascertained to exist in the sauguiferous system,—a fact unequivocally demonstrating that , the assimilating organs had failed to convert the saccharine aliment into the constituent principles of the blood. Oxalic acid is neither found in the blood nor in the urine in a state of health ; but in certain forms of disease probably exists in both fluids. Lactic acid, when in excess, which forma one of the most troublesome kinds of acidity in the stomach, and the frequent concomitant of bilious attacks, is like wise the result of such mel-assimilation generally of the saccharine matter, though occasionally of albuminous hatters. The prohibition
of articles of a decidedly saccharine nature from the diet of diabetic patients becomes absolutely necessary. Not only sugar in its crystallise ble states must be prohibited, but those fruits which contain it. A single peach or pear has occasionally brought back the disease in all its severity. Even those starchy or farinaceons matters which we have seen to be convertible into sugar must be avoided, especially potatoes, the starch of which is, of all others, the most easily transmuted into sugar which is of the same nature as the diabetic sugar.
The abuse of sugar is to be avoided by persons disposed to the oxalic acid diathesis ; and persona of a bilious habit should use it with great moderation, as also those with tendency to rheumatism. (See Prout.,1 Sugar, though prone to fermentation when in h dilute state, possesses when concentrated great antiseptic properties, and is exten sively employed to preserve both animal and vegetable substances from decomposition. Sometimes the sugar existing naturally in many fruits is sufficient to ensure their preservation, as in figs, raisins, and other dried fruits ; especially if the season has been bright and warm, when more sugar is elaborated. In other cases sugar is added, as in many preserves and jellies. Sugar added to meat, fish, &c., renders less salt necessary for keeping them, and preserves more of the natural taste and flavour. Many medicinal substances, as well as flavours and colouring principles, aro preserved by means of sugar. [Secure.] Sugar, from the readiness with which it reduces to a metallic state those bases which have a weak attraction for oxygen, has been proposed as an antidote in cases of poisoning with copper, corrosive sublimate, Itc. It is to be doubted whether syrup is adequate to effect the reduc tion at the temperature of the stomach. On the other band, sugar yields oxygen to those substances which attract it strongly, such as phosphorus; hence nothing so quickly and certainly revives a fire nearly extinct as throwing a little brown sugar on the embers. Sugar burnt at a low temperature constitutes caramel; one part of this dissolved in four parts of water constitutes the liquor (improperly called tincture) saceliari testi, which is employed as a coleering matter for many liquids, especially for the dark-coloured sherries and other wines.
Refined sugar is much employed for the administration of volatile oils constituting foleo-eaceharunis. Finely powdered white sugar sprinkled upon ulcers with unhealthy granulations acts as an escharotie.
The term sugar has been applied to some substances on account of their sweet taste, which are widely different from real sugar, and possess even poisonous properties, such as acetate of lead, or sugar of lead. Oxalic acid, another very poisonous substance, is often called, from being prepared from sugar, ac-id of sugar, and therefore thought to be harmless. Fatal accidents frequently result from this mistake. [OxALic Acin.]