SUGAR REFINING.
When brown or raw sugar is refined it forms the white crystalline product known as loaf sugar. The process involves many ingenious arrangements in its detail, but the essential object to be obtained is the separation of all coloring matter from the raw material without producing any more by the process, which is a greater difficulty than would at first appear, for all solutions of sugar evaporated in the open air become to a great extent colored, and the longer the exposure, and the higher the temperature, the worse the product; a substance forming called “caramel,” which discolors it.
FIG. 1.
FIG. 2.
The brown sugar is first mixed with a very small quantity of boiling water, just sufficient to form a thick pasty mass, which is put into conical pots (figs. 1 and 2), and allowed to drain, the small quantity of water washes out only the brown part, and leaves the crystals pretty white; they are then dissolved in water, mixed with some bone-black and bullock’s blood; the bone-black is the charcoal from burnt bones, and has the power of taking away the color of most vegetable solutions, the bullock’s blood is used as affording a cheap kind of albumen, which when the solution of sugar is boiled coagulates and entangles all the floating matters so that they may be removed by filtration.
VACUUM-PAN.
FIG. 3.
The liquid is boiled for a time, and then put into a cistern excluded from the light, having holes at the bottom into which long tubes of thick twilled cotton are fastened, through which the solution runs as bright as water; they all hang down into another cistern below, also kept from the light, from which it is pumped up into the evaporating apparatus—a copper vessel entirely air-tight, heated by steam and having a powerful air-pump attached to it by which all the vapour and air are removed as the syrup becomes hot; this is called a “vacuum pan” (see [engraving]), and by this the syrup is condensed to the proper consistence, and is put into moulds of the shape the loaf is to be, having holes at the lower part which are plugged up, the syrup as it cools forming a solid mass of crystals; these moulds are arranged in rows over a channel leading to a proper receptacle, the plugs are taken out from the holes at the bottom of each and some pure concentrated syrup is poured on to the upper part; this slowly descending filters through the sugar, carrying with it any “caramel” that may have formed, finally escapes at the hole, and runs into the cistern; this completely whitens the sugar, and gives it a brighter and coarser grain. The loaves are then taken from the moulds, dried in an oven at a gentle heat, and finally packed in paper for sale. If the pointed ends are discolored or ragged the loaf is put into a lathe ([fig. 3)] and the end turned to a proper figure or cut off.