83 



SUGAR, PROPERTIES OF. 



SUGAR, PROPERTIES OF. 



89-1 



game sort, as in the sugar from the sugar cane, which yields both th e 

 finest crystals and likewise molasses or treacle. It almost invariably 

 exists in a dilute and liquid state in plants, but it occasionally exhibits 

 a crystalline form in the flower of certain plants, such as the Shododen- 

 drmponticum, the Strelit:ia Rcyince, and Eucomii punctata. Sugar is 

 the great principle by which rapidly-growing succulent parts of plants 

 and seeds, when they germinate, are nourished. Hence it is produced 

 in large quantities in such seeds as contain starch, when excited to 

 germinate, as may be observed in the process of malting, which up to 

 a certain stage is exactly that of the germination of the seed. Under 

 these circumstances, seeds which are insipid from the bland nature of 

 the starch which they contain become sweet. By this means many 

 seeds which are regarded as little suited for the nourishment of man 

 may be made to contribute to his support, by merely steeping them in 

 water till they sprout. A similar transformation of starch into sugar 

 takes place in the ripening of many fruits. Thus the fruit of the 

 banana, or plaintain, which, when gathered green, abounds in starch, 

 if allowed to ripen on the stalk is destitute of starch, and yields much 

 gummy and saccharine matters. The same happens when the palms 

 are about to flower, as all the starch in their lofty stems is rapidly 

 transformed into sugar; and hence the sago-palm (Sar/us liumphii, 

 &c. ) and the Muuritla Jleu:uosa (sago-palm of the Orinoco) are cut down 

 just when the flower-buds begin to appear, to obtain the sago they 

 contain. In other palms the flower-buds are allowed to protrude, and 

 a wound being made in the spatha, a large quantity of a sweet fluid 

 , which may either be concentrated by boiling, when sugar is 

 deposited, or the liquid may be fermented, and so yield the faddy 

 called palm wine. If these, or the sugar-cane, maize, or our common 

 esculent roots, parsnep, skirret, carrot, or beet, are allowed to flower, 

 all the gummy and saccharine matters disappear from the roots or 

 stem. The transformation of starch into gum and sugar is effected by 

 a principle called diastase [FERMENT], which is so powerful, that " one 

 part of it is sufficient to render soluble the interior portion of two 

 tliu.<md parta of starch, and convert it into sugar." Wherever buds 

 are lodged, there the elements of diastase are placed, to come into play, 

 when they begin to sprout, and supply them with food in a state of 

 solution, as is the case with the buds or eyes of potatoes. 



Many seeds, before they are ripe, contain a saccharine substance, 

 \\hich is changed into starch when fully ripe, but which again becomes 

 sugar in germinating, such as the garden pea. Many stems of grasses 

 ..ret at an early stage of their growth, but become insipid at a 

 Liter period. This influences greatly the nutritive powers of these 

 grasses, according to the stage of growth when they are cut down and 

 made into hay. (See appendix to Davy's ' Agricultural Chemistry.') 

 Those which have been allowed to become too ripe are often [restored 

 to a proper state by the fermentation (heating) which occurs after the 

 hay in stacked ; but this is sometimes so violent as to consume the 

 rick. 



The starch lodged in the stem of certain trees in autumn is con- 

 verted, by the ascending sap in spring, into sugar, with great rapidity. 

 This is the case with the Acer taccharinum, or sugar-maple, and many 

 other species of that genus which are tapped in February. 



The same U the case with the ascending sap of the birch-tree, but 

 this does not contain sufficient sugar to permit the concentration of it; 

 there is enough however to undergo the vinous fermentation, and 

 thereby furnish the agreeable beverage called birch wine. 



Next to the sugars from the cane and beet-root, among those which 

 are crystallisable and capable of fermentation, the most important is 

 the granular sugar obtained from a great variety of sources. It exists 

 in considerable quantity in the juice of grapes, and hence the name 

 i/m/ie mi/ar, which should be limited to this particular variety, is 

 imui extended to the whole class of krummel sugars. It forms 

 a constituent of a great many fruita, not merely fleshy, such as pears 

 cherries, peaches, melons, dates, figs, grapes, on which last two il 

 forms a white incrustation when these are dried, but in chesnuts 

 when produced in warm regions. It exists in the nectaries of many 

 flowers, and is collected by the bees ; hence honey is only one of the 

 kinds of this sugar. Though harmless in probably all instances to 

 tli' bees, from whatever plant collected, it not unfrequently has a 

 poisonous influence over human beings, when it has been collected 

 from poisonous plants, such as Rhododendrons and their allied genera 

 Granular sugar is readily formed by the action of dilute sulphuric 

 acid on starch, or sugar of milk, or the bollard sugar which remains 

 after the finest refined sugar has been procured from the cane or beet 

 root sugar. Lignin, or anything containing or formed from it, such as 

 saw-dust, linen-rags, or paper, may be likewise transformed into 

 granular sugar. It is likewise the kind of sugar formed during the 

 germination of seeds. Lastly, it is that kind of sugar which is formet 

 by a perverted action of the digestive and assimilating organs in the 

 **"nr termed diabetet mdlitta. [DIABETES.] All these varieties taste 

 less sweet than the cane-sugar, and also differ among themselves ; thus 

 grape and honey sugar are sweeter than that from starch, while starch 

 sugar is sweeter than that obtained from juniper berries. All of them 

 i in less carbon and more water than the cane sugar, and may 



1 1 as hydrates of sugar. 



ir, which, though with difficulty crystallised, in referred to this 

 section, exists in many fungi or mushrooms, especially of the genus 

 Agariciis. Wbile it contributes to their nutritive properties, it mos 



ikely proves one source of the poisonous qualities they sometimes 

 possess, as it is occasionally transformed into oxalic acid. Masses of 

 crystals have been observed on the cap of a mushroom, some of which 

 were sugar, while others were oxalic acid. Free oxalic acid is found in 

 the Polyporus sulphiireus, "Bull., which is most likely formed at the 

 expense of the sugar. 



The only uncrystallisable sugar which is capable of fermentation is 

 he syrup which remains after the refining of the cane and other sugars. 

 :t receives the name of molasses, and is used in medicine under the 

 name of Sacchari faex, which is preferable to that of theriaca, as 

 this might lead to confusion with a poisonous compound which bears 

 a similar name. Molasses are largely employed for the distillation 

 of rum. 



The kinds of sugar unsusceptible of fermentation are, the sugar 

 of milk and mannite ; yet sugar of milk, when by the action of 

 dilute sulphuric acid it is converted into granular sugar, is as 

 susceptible of fermentation as any of the above-described. In other 

 respects it conducts itself like common sugar, except that with nitric 

 acid, besides oxalic acid, jt forms saclactic acid. It is procured from 

 whey, either simply by evaporating to dryness (saccharum lactis insjits- 

 satum), or by crystallising it. It is frequently separated from the 

 curd by the addition of a great many substances, which can coagulate 

 this, such as alum, vinegar, tamarinds, and mustard, and in certain 

 diseases these medicated wheys are much recommended. 



Sugar of milk has little sweetness, but a hot solution of it 

 tastes much sweeter than the dry sugar. Sugar of milk is much 

 used by the followers of homojopathy as the material of their dynam- 

 ised globules. 



Manna sugar constitutes the greater portion of the manna which 

 lows from the Ornus europaea and other ashes in the south of Europe, 

 the bark of the olive-tree, many species of pines, the root and leaves 

 of celery, the bulb of the common onion, and in the rhizome of the 

 Tnticam repent, or couch-grass. The sweet juices of many plants, 

 such as beet, carrots, &c., when long exposed to the air, generate 

 manna sugar by a partial fermentation. To prevent this is one of the 

 great objects in the manufacture fof beet-root sugar ; hence the neces- 

 sity for speedily concentrating and purifying this juice. To this variety 

 of sugar probably belongs Cynodon, which exists in the root of 

 Digitaria (Cynodon) Daclylon. And also the principle called caiitlltn, 

 obtained from canella alba. 



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 Pencea mucronata, P. Sarco- 

 colia, 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 unsusceptible of fermentation, and ought to be considered in 

 conjunction with it, from the share it may have in augmenting the 

 sugar in diabetes. (See 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 negroes, 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, supermalate 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, in ' 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 be 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 ; hut in diabetes, sugar has been repeatedly ascertained to exist 

 in the sanguiferous 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 



