GARANCEUX .

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combined with the material, and not removable by washing with water alone.The experiments made by Schwartz with oily extracts from garancin yieldedshades as fast and beautiful as those from flowers of madder, while the additionof the ligneous matter from garancin was alone sufficient to impair thesecharacters.

Some manufacturers add to the garancin, after having been stove-dried andwhile being ground up, a small quantity of bicarbonate of soda or precipitatedchalk, well washed and dried, in order to absorb the acid. It has also beenproposed to improve garancin by exposure to the vapours of ammonia, and todry the material afterwards by steam.

Garanceux.

The manufacture of garanceux from spent madder is essentially the same asthat of garancin, and the same general explanations apply equally to either.The method of making garanceux is simple and well understood, and requiresnothing but care and attention to yield regular results. The spent madderfrom the dye-beck and wince pits is collected in a sufficiently large pit andallowed to settle, usually with the addition of weak sulphuric acid, which bothstops any inclination to fermentation and throws down a fine powder whichotherwise floats in the liquor. The wet mass should be well pressed, until itdoes not contain more than two-thirds of its weight of water. Instead of apress, the centrifugal hydro-extraCtor—as used in sugar-refineries—is oftenused, with the advantage that it is not needful to break the matter up after-wards. The quantity to be used of the acid may vary, but a dozen pounds ofbrown acid (chamber acid) is a good proportion to the hundredweight of spentmadder. The acid should be mixed, before being added to the madder, withabout 3 gallons of water. It is essential that the acid touch all the particlesof madder, and therefore the material should be thoroughly worked through ;after which the mass may be left for days, or even weeks, before it is steamed.The operation of steaming must be watched, to see that all the madder gets afair proportion of steam. If the spent madder be too moist it sets in thesteaming cisterns, and forms chinks, through which the steam blows withoutpermeating the whole mass. It should be so moist as to yield water uponpressure between the fingers, but not wet enough to stick together whenpressed in the hand. The thorough washing of the garanceux is of courseimportant, but it has the advantage of washing much faster and more easilythan garancin, on account of its loose structure. The washing is known to beaccomplished by the liquor no longer tasting acid, and by the appearance of afine slimy powder, which never shows till the washing is almost completed.It is not advisable to use any alkali to neutralise the remainder of the acid,but it is sometimes done, and then crystals of soda or milk of lime may beadded in proper quantity. It keeps better if left a little acid, and can beneutralised in the dye-beck with safety. When the washing is complete itshould be pressed again.

Well pressed garanceux contains between a third and a fourth of its weightof dry matter, the remainder being water. Its tinctorial value, in proportionto garancin of the first quality, will vary according to the nature of the madder,

state of bicarbonates and of ammonia gas—has (unless very carefully applied and skilfullyManaged) the effedt of injuring the garancin. Many years ago Drs. van Ylaanderey and I3aum-haucr proved garancin to contain ligno-sulphuric acid.