The root more or less deprived of its bark, sliced and dried, of Rheum palmatum, Rheum officinale, and probably other species. Collected and prepared in China and Thibet.

Characters. - Trapezoidal, roundish, cylindrical, or flattish pieces, frequently bored with one hole, yellow externally, internally marbled with fine waving greyish and reddish lines, finely gritty under the teeth; taste bitter, faintly astringent and aromatic; odour peculiar.

Composition. - The chief constituent is chrysophanic acid, so-named from its forming briliant yellow crystals. It is extracted by ether or alcohol, not by. water. Besides this there is also a glucoside chrysophan, which splits up into chrysophanic acid and sugar. There are also several resinous matters, one of which, phaoretin, is purgative, and mineral compounds are also present, especially oxalate of calcium. The astringency of rhubarb is due to a peculiar tannic acid (rheo-tannic), which is soluble in water and alcohol, but not in ether.

Impurities. - English rhubarb and turmeric fraudulently added. Tests. - Odour and taste (English rhubarb). Boracic acid does not turn the yellow exterior brown (turmeric).

Dose.- Of the powdered root, 1-5 gr. as a stomachic; 10-30 gr. as a purgative.

Preparations.

B.P.

Dose.

Extractum Rhei.........................................................................

5-15 gr.

Infusum Rhei (1/4-OZ. in 1/2-pint for 1 hour).........................

1-2 fl. oz.

Pilula Rhei Composita (vide p. 523).........................................

5-10 gr.

Pulvis Rhei Compositus...........................................................

5-10 gr. (child).

,, ,, ,, ............................................................

20-60 gr. (adult).

Syrupus Rhei.............................................................................

1-4 fl. dr.

Tinctura Rhei.............................................................................

1-2 fl. dr. (stomachic).

,, ,, ...........................................................................

1/2-1 fl. oz. (purgative).

Vinum Rhei ..............................................................................

1-2 fl. dr.

U.S.P.

Rheum.

Extractum Rhei..........................................................................

3-10 gr.

Extractum Rhei Fluidum............................................................

1-10 min.

Pilulae Rhei (vide p. 523)..........................................................

1-3 pills (3 gr. each).

Pilulae Rhei Compositae (vide p. 523)......................................

1-4 pills.

Pulvis Rhei Compositus .............................................................

30-60 gr.

Syrupus Rhei...............................................................................

1-4 fl. dr.

for children.

Syrupus Rhei Aromaticus...........................................................

1-4 fl. dr.

Tinctura Rhei..............................................................................

1-6 fl. dr.

Tinctura Rhei Aromatica............................................................

1-4 fl. dr.

Tinctura Rhei Dulcis...................................................................

1-4 fl. dr. for children.

Vinum Rhei.................................................................................

1-4 fl. dr.

Mistura Rhei et Sodae.......................................................................................................

2 dr.-3 oz.

B.P. Pujvis Rhei Compositus. Compound Powder of Ehubarb (Gregory's

Powder). - Rhubarb root, 2 oz.; light magnesia, 6 oz.; ginger, 1 oz. Mix the powdered ingredients and pass through a fine sieve.

B.P. Syrupus Rhei. Syrup of Rhubarb. - Rhubarb root and coriander fruit, both in coarse powder, each 2 oz.; refined sugar, 24 oz.; rectified spirit, 8 fl. oz.; distilled water, 24 fl. oz. Percolate the rhubarb and coriander with the spirit and water; evaporate the filtrate to 13 fl. oz.; filter; dissolve the sugar in the filtrate.

B.P. Tinctura Rhei. Tincture of Rhubarb. - Rhubarb, 2 oz.; bruised cardamom seeds, 1/4 oz.; coriander fruit, 1/4 oz.; saffron, 1/4 oz.; proof spirit, 1 pint.

B.P. Vinum Rhei. Wine of Rhubarb. - Rhubarb root, 1 1/2 oz.; Canella alba bark, 60 gr.; sherry, 1 pint.