Prop. It is less sweet and less soluble than cane sugar, requiring 11⁄2 part of cold water for its solution; instead of bold crystals, it forms granular warty masses, without distinct crystalline faces; it does not easily combine with either oxide of calcium or oxide of lead; with heat, caustic alkaline solutions turn it brown or black, but it dissolves in oil of vitriol without blackening, the reverse being the case with cane sugar; with chloride of sodium it forms a soluble salt, which yields large, regular, and beautiful crystals. Sp. gr. 1·400.
The various fruits contain grape sugar in the following proportions:
| Per Cent. | ||
| Peach | 1·57 | |
| Apricot | 1·80 | |
| Plum | 2·12 | |
| Raspberry | 4·00 | |
| Blackberry | 4·44 | |
| Strawberry | 5·73 | |
| Bilberry | 5·78 | |
| Currant | 6·10 | |
| Plum | 6·26 | |
| Gooseberry | 7·16 | |
| Cranberry | 7·45 | (according to Fresenius). |
| Pear | 8·02 to 10·8 | (E. Wolff). |
| Apple | 8·37 | (Fresenius). |
| ” | 7·28 to 8·04 | (E. Wolff). |
| Sour cherry | 8·77 | |
| Mulberry | 9·19 | |
| Sweet cherry | 10·79 | |
| Grape | 14·93 |
Obs. Cane sugar is converted into grape sugar during the process of fermentation, and by the action of acids. See Sugar, and Sugar, starch (below).
Sugar, Maple. Syn. Saccharum acerinum, L. From the juice of the sugar maple. It is identical with cane sugar.
In the United States and the British Colonies of North America considerable quantities of this sugar are made. The juice is obtained by boring through the bark of the tree to a depth of about a quarter or half an inch. Each tree has generally two perforations made in it, and they are always made on that side of the tree which faces towards the south, and at a distance of about 20 inches from the ground. The juice flows into suitable vessels, into which it is conducted by reeds placed under the perforations. The period chosen for tapping the trees is that during which it is known the sap is ascending, from March to May. Sometimes the tree undergoes a second tapping in the autumn, but this is not generally practised, inasmuch as it is injurious to the tree. A daily yield of 6 galls, of juice from each incision is looked upon as a ‘good run,’ and if this 6 gall. be the produce of an old tree or ‘old bush’ they will yield 1 lb. of sugar. In a young tree or ‘young bush’ the yield of sugar from the same quantity of sap is only half. By proper care the same tree may be tapped 20 or 30 years following. Unlike the sugar-cane the juice in the maple is the richest in sugar the higher it is found from the ground. The concentrated saccharine liquid is concentrated every 24 hours. The raw crystallised sugar undergoes no refining, and being made into blocks is then sent to market.
Sugar, Milk. C12H22O11.H2O. Syn. Sugar of milk, Lactin; Saccharum lactis (Ph. D.), L. Prep. Gently evaporate clarified whey until it crystallises on cooling, and purify the crystals by digestion with animal charcoal and repeated crystallisations.
Prop., &c. White, translucent, very hard cylindrical masses or four-sided prisms; soluble in about 6 parts of cold and in 2 parts of boiling water; nearly insoluble in alcohol and ether; ammoniacal plumbic acetate precipitates
it from its solutions. When an alkaline solution of grape sugar is boiled with the salts of copper, silver, or mercury, it reduces them; it produces right-handed rotation of a ray of polarised light; by boiling with dilute acid it is converted into galactose (C6H12O6); treated with nitric acid it yields mucic acid, with small quantities of saccharic, oxalic, and tartaric acid. Milk sugar is unsusceptible of the vinous fermentation, except under the action of dilute acids, which convert it into grape sugar; in solution, it is converted into lactic or butyric acid by the action of caseine and albuminous matter. Milk contains about 5% of it. (Boussingault.)
Obs. Sugar of milk is chiefly imported from Switzerland. In this country it is chiefly used as a vehicle for more active medicines, especially among the homœopathists.