SUBSTITUTES FOR MADDER.

329

Avignon madder as regards its qualities as a dye-stuff, but being acid, as is thecase with all the Indian Rubiacece in a very high degree, it requires theaddition of chalk in the dye-beck; the colours produced upon fabrics are inevery respedt the same as those produced by madder, and are also the samewith the same mordants. The chayaver, however, hardly contains the fourthpart of colouring matter found in madder, taking, of course, equal weights ofeach.

Mungeet, or Rubia mungista, is characterised by the peculiarity that thestem contains more colouring matter than the root. In a dried state it isalmost as rich in colouring matter as good Avignon madder, but it containsmuch acid and a great deal of yellow colouring matter; it does not yield fastshades at all, and, even with the treatment for Turkey-red, the cleared red—at first bright and beautiful—is rapidly destroyed by sunlight. Dr. Stenhouse*has made some researches on this mungeet which prove that it does not con-tain alizarin or purpurin, but a peculiar colouring matter which this chemisthas called mungistin. To obtain this, the previously pulverised root istreated with a boiling solution of alum (500 grms. of mungeet root, 1 kilo, ofalum, and 8 kilos, of water) ; the liquid, having been filtered, is boiled, whenthere is thrown down a bright red precipitate, which is collected on a filter,washed, and dried. The dried material is treated with sulphide of carbon,which dissolves the colouring matter, while a resinous substance is left. Thesulphide of carbon solution yields, on evaporation, a bright red residue, con-sisting of mungistin and purpurin. When this is adted upon by boiling wateracidified with acetic acid, the purpurin is left undissolved, while the mungistinis taken up, yielding a yellow solution as long as the fluid is hot, but oncooling the mungistin is thrown down. This precipitate is purified by meansof boiling alcohol, from which the mungistin crystallises out on cooling.This substance is sparingly soluble in cold, but more freely in hot, water;slightly soluble in cold, but readily so in boiling, alcohol. Mungistin is fusibleby heat, and crystallises again on cooling : it dissolves in aqueous solutions ofthe carbonates of potassa and soda, and the caustic alkalies and ammonia,yielding bright red solutions. With baryta water it yields a yellow precipitate,and hydrate of alumina forms with it a bright orange lake. Mungistin issoluble in strong sulphuric acid ; its formula is, according to Dr. Stenhouse,C8H6O3 : concentrated nitric acid converts mungistin into phthalic and oxalicacids; highly concentrated ammonia converts this body into a brownish humus-like substance.

Under the name of nona is designated the root of a rubiaceous tree belongingto a species of guilandina. This root has great similarity with madder root, butis more difficultly pulverised, and contains a large quantity of yellow colouringmatter and much acid, so that previous to being fit for dyeing it should bewashed with water, and in order to render the colours fast carbonate of sodais required to be added to the dye-beck. According to the experiments madeby Messrs. Schwartz and Koechlin, the nona root should be first ground to afine powder, next washed with fifty times its weight of pure cold water, afterwhich it is fit for the dye-beck, with the addition of one-fifth of its weight ofcarbonate of soda. The initial temperature should be about 39°, and graduallybe raised to boiling: in this manner previously oiled and mordanted cloth

* See " Annalen der Chemie und Pharmacie,’’ vol. cxxx., p. 325.