DEXTRIN (from Lat. dexter, right, referring to its power of turning to the right the plane of polarised light ). .\ nana• applied to several organic substances produced by the action of malt extract, saliva. or panereatie juke upon starch paste, the first product of the (ransforma tion being soluble starch, and dextrin being pro duced by the hydrolysis of the latter. A con tinuation of the hydrolytic action results in the formation of sugars. The principal dextrins are: erythro-dextrin. achroMextrin, and malto dextrin. all of which have the relative com position as starch— (C.11,00011 ; their molecular weights, however, ace unknown. A•hroiklextrin may be prepared by the prolonged action of saliva or pancreatic juice on starch paste; when the solution ceases to be colored by the addition of iodine, that is to say, when all the starch has been transformed, the solution is concen trated by evaporation and precipitated with alcohol. The substance thus obtained is com pletely freed from maltose by warming with mercuric cyanide and caustic soda and may be further purified by dissolving in water and reprecipitating with alcohol.
Dextrin (British gum or starch gum) is often used as a substitute for gum arable in the processes of calico-printing, and for stiffening different goods: it is also applied to the back of postage stamps. Its value as a substitute for
gum consists in its hieing more flexible and less brittle, when dry, than that substance. For com mercial purposes it is prepared on a large scale either by moistening potato-starch with weak nitric acid, then drying and heating to 110° C., or by simply heating the starch to about C. When thus prepared. dextrin contains consider able amounts of dextrose and unaltered starch.
DEY, do (Turk. dal, maternal uncle). A title applied colloquially to any elder. especially in former times among the Janissaries; conse quently, when the commander of that corps was associated with the Turkish pasha in the govern ment of the name was retained for him, and then transferred to any pasha or regent. Early in the eighteenth century the Dey of Al giers emancipated himself from the authority of the Sultan. Tunis and Tripoli were also some times ruled by deys in place of the hey. See BEG.