QUERCITRON.

397

gradual precipitation. Nitric acid colours quercitrin orange-red, andconcentrated sulphuric acid dissolves it. Quercitrin is a bright yellowcrystalline, inodorous powder, of a somewhat bitter taste and feebly acidreaction. Under the lens the powder appears as small rectangular tubularcrystals. As obtained by the cooling of an aqueous solution quercitrin hasthe appearance of a mother-of-pearl-like shining bright yellow substance.When submitted to heat it yields a yellow sublimate, and leaves an abundantresidue of charcoal. There exists some uncertainty as regards the proper formulaof quercitrin ; several which have been proposed agree each with the results ofthe elementary organic analysis, but since certain experimenters have over-looked what was proved by Dr. Hlasiwetz, that quercitrin does not becomecompletely anhydrous below 200°, retaining a part of its water of crystallisationnearly to that temperature, it is conceivable that there exist discrepancies inthe centesimal results of the elementary analysis. Quercitrin is a glu cosidecapable of being split up into a kind of sugar, and a yellow principle,“quercetin;” the formula to be assigned to quercitrin will therefore to acertain extent, and within the limits of a more exadfc chemical analysis,depend upon the formula of quercetin, and since we cannot discuss theconstitution of the latter as yet, we give here the centesimal results ofthose analyses of quercitrin which appear most correct:—

Dried at 200°

/ - 1 -N

MM. Zwenger MM. Hlasiwetz Incompletely dried,

and Drouke. and Pfaundler. ,- 1 -\

Carbon .. 56-0 562 557 54-1 .52-4

Hydrogen 4-6 47 5'2 5-2 47

According to the researches of M. Rigaud,* an aqueous solution ofquercitrin acidified with sulphuric acid and boiled becomes turbid, and de-posits even while yet hot an abundance of a flocculent material far moredeeply yellow than quercitrin, and nearly insoluble in boiling hot water.This phenomenon is best seen by heating together pure quercitrin and water,to which one-tenth of sulphuric acid is added; at a moment when the tem-perature is sufficiently high the quercitrin becomes dissolved, and a momentafter the liquid turns suddenly intensely yellow, next turbid, and thendeposits flakes of quercetin. The liquid from which the quercetin has

been separated by filtration is first treated with carbonate of baryta toeliminate the sulphuric acid, and is, after filtration, evaporated, thus yieldinga syrup, which, according to Zamminer, may become a crystalline mass. Thesugar is not possessed of rotatory power; it reduces alkaline solutions ofsalts of copper, and its composition corresponds to glucose (C6 H i2 0g).

Hlasiwetz and Pfaundler have come to other results; the evaporation ofthe syrup yielded them after a few hours a beautiful crystalline substance,which crystallographically agrees with saccharose or cane-sugar; thesecrystals dissolve at 18° in 2’og parts of water, and also in absolute alcohol;they taste sweeter than glucose, and defied the plane of polarisation to theright (specific deviatory power = 0-0763°). This sugar is incapable of fermen-tation, and its formula is C 6 H I2 0 3 + H 2 0 . The last molecule of water maybe eliminated at no°; it reduces the cupreous test liquor, and fuses at 107°. Iftreated with a mixture of concentrated nitric and sulphuric acids, the sugar just

* “ Annalen der Chcmie und Pharmacie,” xc., 283.