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may also be met with in free state. Its properties rather differ in differentplants; its chemical features are simultaneously those of a weak acid, whichcan enter into combination with alkalies and metallic oxides, and of a poly-atomic alcohol approaching to phenol. The alkaline solutions are orange orbrown-coloured, and do not change perceptibly when left in contact with air;heated along with ammonia, contadt of air being excluded, an amide isformed remarkable for its ready oxidation in contact with air.

Hlasiwetz has proved that when fusing caustic potassa or sodium amalgam adtsupon an alkaline solution of this body it is converted into a saccharine matterand phloroglucin (C6H6O3), frequently accompanied by a colourless acid.When sodium amalgam is placed in contadt with an acidified alcoholic solutionof this substance it is molecularly changed and converted into a red isomericprinciple.

Anhydrous acetic acid heated to 140° with this quercetric yellow convertsit into an acetic derivative, the hydrogen of the orginal body being partly re-placed by acetyl. The quercetric glucosides or the yellow-coloured bodyobtained therefrom can only be fixed on textile fibres by the aid of metallicmordants. With hydrate of alumina a yellow shade is obtained, with ironmordants olives, and with oxide of tin yellows or oranges. Quercitron barkis the inner bark of some species of trees belonging to the natural order ofAmentaceze, and botanically known as Quercus nigra , digitata , trijida , andtinctoria. The Qticrcus nigra , or black oak, so called because the outerepidermis of the bark is black, is a native of the middle and southern statesof the U.S. of America. It is a tree attaining a height of from 25 to 30metres, abundantly met with in the forests of Pennsylvania, Georgia, andCarolina. Quercitron bark, as met with in commerce, is a mixture of fibresand fine powder of a yellow or buff colour. Its preparation is very simple;the bark previously deprived of its black epidermis is ground under millstones,and the fibrous portion (which is the least valuable) is sometimes separatedby means of sieves. Three kinds of quercitron are distinguished in commerce,imported from Philadelphia, New York, and Baltimore, the first being generallypreferred.

The celebrated Bancroft was the first to apply (1775) this now highly ap-preciated dye-ware. The decodtion of quercitron exhibits an orange-yellowcolour. If exposed to air it very slowly deposits its colouring matter(quercitrin or quercin) in a crystalline state. After standing for a long timethus exposed the colour turns brownish red, and at last it becomes a thickclotted mass. Its properties are: odour of the oak bark decodtion, like thatof freshly charged tan pits; taste, bitter astringent; readtion, acid to test-paper; the addition of alkalies and alkaline earths deepens the colour of thedecodtion, the latter simultaneously producing a reddish flocculent precipitate.With the undermentioned substances the decodtion of quercitron yields thefollowing readtions :—

Alum, a very slight precipitate; proto and bichloride of tin, acetate of lead,acetate of copper, chloride of barium, nitrate of silver, yield yellow precipitatesverging upon red or olive ; salts of iron, a green colouration and o\ive pre-cipitate ; mineral acids render the colour of the decodtion brighter, and producea flocculent precipitate ; acetic acid merely brightens the colour; solutionof gelatin gives a flocculent precipitate. The more interesting immediate