Fig. 1.
Fig. 2.
The boiling-pan (B) consists of two air-tight hemispheres, surmounted by a funnel, connected by the tube (l) with the condenser (A). The apparatus is supplied by steam by (r s), the steam circulating in the boiling-pan by means of the pipes (g), fig. 2. By opening the lever valves (f) the juice can be run by means of the pipe (o) into the pan (p). When the pan, after continued boiling, requires to be refitted, the pipes (l and w) are connected to an air-pump. The manometer (h) shows the state of the air pressure, which can be regulated by opening the pipes connected to the vacuum chamber. By means of the gauge cylinder (G) the quantity of syrup in the boiling-pan can be ascertained, the gauge cylinder being connected to the boiling-pan by the pipes (a and i), and the height read off from the gauge tube (n). The syrup can be removed, for the purpose of ascertaining its consistency, from the gauge cylinder by means of either of the three pipes (b, c, d). By u steam can be admitted to the boiling-pan and condenser. e is generally of stout glass, and enables the state of the juice to be seen. g is the grease cock, f the manhole. The condenser consists of the jacket (B), arranged to prevent the mixing of the juice with the water used for condensation. x is the gauge. The pipe (m) conveying water to the condenser terminates in a rose. z is a thermometer showing the interior temperature of the boiling-pan.
The air-pump being set in operation the tube (c) is opened, and the gauge cylinder filled by the juice rising from q. By closing m and opening y the juice is admitted to the boiling-pan. When this is half full the steam pipe (s) is opened, the steam quickly heating the contents of the pan to the boiling point. The condenser is then placed in working; by opening the pipe (l) the steam of the juice passes into the condenser, where it is speedily condensed, passing with the water through β.
Sugar, Diabet′ic. Grape sugar found in the urine of persons labouring under diabetes. In diabetes insipidus, a substance having the general properties of a sugar, but destitute of a sweet taste, appears to be produced (Thénard.)
Sugar, Gel′atin. See Glycocine.
Sugar, Grape, C6H12O6.H2O. Syn. Glucose, Fruit sugar; Saccharum uvæ, S. fructus, L. This substance is found in the juice of grapes and other fruit, in the urine of diabetic patients, and in the liquid formed by acting on starch and woody fibre with dilute sulphuric acid.
Prep. 1. From the juice of ripe grapes or an infusion of the ripe fruit (raisins), by saturating the acid with chalk, decanting the clear liquid, evaporating to a syrup, clarifying with white of egg or bullock’s blood, and then carefully evaporating to dryness; it may be purified for chemical purposes by solution and crystallisation in either water or boiling alcohol. Like other sugar, it may be decoloured by animal charcoal.
2. From honey, by washing with cold alcohol, which dissolves the fluid syrup and leaves the solid crystallisable portion.