AMMONIAC

gum-resin. This is the inspi ated juice of an umbelliferous plant (the dorema armenia cum ) which grows in Persia. It comes to us either in small white tears clustered together, or in brownish lumps, containing many impurities. It po e es a peculiar smell, somewhat like that of a afœtid a, and a bitterish taste. It is employed in medicine. Its only use in the arts is for forming a cement to join broken pieces of china and gla , which may be prepared as follows: Take isingla 1 ounce, distilled water 6 ounces, boil together down to 3 ounces, and add 1 1 ⁄ 2 ounce of strong spirit of wine;—boil this mixture for a minute or two; strain it; add, while hot, first, half an ounce of a milky emulsion of gum ammoniac, and then five drams of an alcoholic solution of resin mastic. This resembles a substance sold in the London shops, under the name of diamond cement . The recipe was given me by a respectable dispensing chemist.