Caramel, Pure

Prep. 1. (Graham.) Crude caramel, obtained as above, is placed on a parchment-paper dialyser. The undecomposed sugar and certain intermediate compounds diffuse out with considerable facility, and what ultimately remains on the dialyser po e es five times the colouring power of the original crude caramel, weight for weight. See Dialysis . 2. (Peligot.) Add strong alcohol to a filtered aqueous solution of crude caramel until it ceases to produce a precipitate; collect the precipitate, which is caramel, on a filter, wash with alcohol, and dry. Graham recommends that the product should be di olved and precipitated four or five times, or till the ma thrown down, from being plastic at first, becomes pulverulent. 3. (J. J. Pohl.) Cane sugar is heated in a spacious metallic ve el by means of an oil bath to 410° or 419° Fahr. as long as aqueous vapours escape, the ma being occasionally stirred with a spatula. The ma is then finely powdered and digested with alcohol for two or three hours; the digestion is repeated until the fluid no longer tastes bitter. Prop. A solution containing 10% of purified caramel is gummy, and forms a tremulous jelly on standing. Evaporated in vacuo, it dries up into a black shining ma soluble in water; but if the solution be evaporated to dryne by the heat of a water bath, the whole matter is rendered insoluble in hot or cold water. A very small proportion of caramel suffices to give a rich sepia tint to water.