RUMEX 



193 



It is insoluble in ether and readily separates from a dilute alcoholic 

 fluid extract on the addition of ether. 



Compound Powder of Rhubarb. Consisting of powdered rhu- 

 barb, magnesium oxide and powdered ginger. A pinkish-white 

 mobile powder, becoming darker on exposure to air; when examined 

 the compound powder of rhubarb shows a finely granular ground 

 mass of magnesium oxide, numerous starch grains and characteristic 

 fragments of vegetable tissues; starch grains of ginger more or less 

 elliptical or ovoid, frequently with a prominent beak, from 0.005 

 to 0.060 mm. in diameter, starch grains of rhubarb, single or com- 

 pound, either spheroidal or polygonal, often with a central cleft 

 and the individual grains from 0.002 to 0.020 mm. in diameter; 



FIG. 83. Crystals of oxymethylanthraquinones sublimed from rhubarb, a, 

 crystals obtained at higher temperatures; b, crystals obtained by sublima- 

 tion at a lower temperature or may be obtained by re-crystallizing the 

 form shown in (a). After Tunmann, Pflanzenmikrochemie. 



mounts made with solution of hydrated chloral show a strong effer- 

 vescence and show more clearly the fragments of reticulate tracheae, 

 the reddish-brown parenchyma of rhubarb in some of the cells of 

 which occur numerous small starch grains, and the characteristic 

 rosette aggregate crystals of calcium oxalate varying from 0.050 

 to 0.100 mm. in diameter; with solutions of the alkalies many of the 

 fragments become of a deep red color. 



RUMEX. Yellow Dock. The rhizome and roots of the common 

 yellow dock or curled dock (Rumex crispus). The drug is collected 

 in the autumn, freed from adhering rootlets, cut into longitudinal 

 pieces or into transverse segments and dried. 



Description. Usually in small pieces from 1 to 4 cm. in diameter 

 and 3 to 25 mm. in thickness; or split into pieces attaining a length 



