190 



täte of lead a brownish, gold-yellow colour without any deposit, 

 and becomes coloui-less with acids; colours chloride of iron dai-k- 

 brown-green. 



KllsnilllOtailllic Acid. Is obtained in the preparation of 

 rhamnocathartin and is purified by washing, drying, dissolving in 

 ether and evaporating. — Green-yellow, amoi'phous, easily-friable 

 mass of a bitter and acerb taste, fusi])le, dissolves scarcely in cold, 

 slightly in boiling water, readily in alcohol and in ether, colours 

 and precipitates the salts of oxyd of iron olive-green, precipitates 

 also slowly tartarated antimony, but not glue. 



l{IiaiU110Xsllitliill=:Ci2 He Oc or C40 H20 02o- Yellow, crystal- 

 line substance of the bark of the root and of the stem, also of the 

 seeds of Rhamnus cathartica and Rh. Frangula and doubtless 

 many other species. Cover the l)ranchlets of Ilh. Frangula with 

 sulphide of carbon and keep for three to four days, evaj^orate the 

 liquid to dryness, treat the remnant with alcohol, which leaves the 

 fat undissolved, evaporate again and recrystallise in ether. — Citron- 

 yellow, crystalline mass of a dull, silky lustre, without taste or 

 smell; fuses at 226° under evolution of yellow fumes, and subli- 

 mates under partial decomposition in gold-yellow needles; is not 

 soluble in water, dissolves in 160 parts warm alcohol of 80%, and 

 sej^arates from it on cooliiig almost completely; scarcely soluble in 

 ether, soluble in sulphide of carbon, fixed and volatile oils, in con- 

 centrated sulphuric acid with dark-ruby-red colour and reprecipi- 

 table by water, in hot concentrated nitric acid unaltered; in 

 alkalies with a splendid pur})le colour. 



Rhapoiiticill ) ^Chrysophanic Acid. 

 Rheic Acid ) 



[KhillsUlthill=C58 H52 O40 + sHO. Glucosid, discovered by 

 Ludwig in the seed of Alectorolophus hirsutus. To prepare it 

 treat the pulverised seeds with strong, boiling alcohol, evaporate 

 the filtrate to dryness, remove the oil by means of ether, dissolve 

 the residue in water, filter and evapoi-ate to a syrupy consistence. 

 TJie crystals, which will slowly form, are to be purified by recrj^s- 

 tallisation. — The R. forms colourless crystals of a bitter-sweet 

 taste; is readily soluble in water and in alcohol, not in ether; of a 

 neiitral reaction. It is not preci})itated liy subacetate of lead, 

 i-educes ammoniacal silver solution when warmed, and separates 

 with acids into glucose and a dai'k-blue-green body, soluble in 

 alcohol but not in water. Heated with sulphuric or hydrochloi'ic 

 acids, R. turns brown, while emitting an aromatic rye odour.] 



Kliodeoretiii = Convolvulin. 



IMiOdotailllic Acid=Cu Ho O7. In the leaves of Rhododen- 

 dron ferrugineum and probably many of the congeners. Distil 

 the alcoholic extract; mix the renmant with water, filter^ precipi- 



