168 ULUCOSIDES OTHER THAN TANXIXS. 



water, but the latter solvent dissolves it with facility when 

 Avaimed. Dilute sulphuric acid resolves it into glucose, hydro- 

 quinone and methyl-hydroquinone. Both of the latter can be 

 extracted hy shaking with ether, and, when warmed with dilute 

 sulphiu-ic acid and peroxide of manganese, yield quinone, recog- 

 nisable by its characteristic iodine-like odour. Acetate of lead 

 does not precipitate arbutin. 



Daphnin^ differs from arbutin in being precipitated by acetate 

 of lead. It is sparingly dissolved by cold, but freely by warm 

 water and by alcohol, and is insoluble in ether. Alkalies colour 

 it yelloAv. Acids and ferments resolve it into sugar and daph- 

 netin ; the latter can be partially sublimed without decomposi- 

 tion. Certain other constituents of mezereon bark yield umbelli- 

 ferone (§27) by dry distillation. 



Salkin crystallizes in colourless needles and scales, which have 

 a powerful action on polarized light, and are freely soluble in 

 boiling water and alcohol, but much less so in cold. It is insolu- 

 ble in ether. From aqueous solution it can be extracted by 

 amylic alcohol (§ 56). Hydrate of lead does not coml^ine with it. 

 Boiling with dilute acids decomposes salicin into sugar and sali- 

 genin or saliretin, both of which substances can be removed by 

 .shaking with ether. If an aqueous solution of salicin or saligenin 

 is boiled with dilute sulphuric acid and liichromate of potassium, 

 salicylous acid is produced. (Cf. § 25.) Cone, sulphuric acid 

 dissolves salicin, saligenin, and saliretin with production of a fine 

 red colour. Salicin strikes a beautiful violet Avith Fröhde's reagent. 

 These reactions can also be employed for the microchemical detec- 

 tion of salicin. 



FupnluL yields benzoic acid in addition to the above-mentioned 

 decomposition-products when acted upon by dilute acids (cf. 

 § 26), and salicylous acid when warmed with chromic acid. With 

 cone, sulphuric acid a red colouration is developed, and with 

 Fröhde's reagent a violet, which, however, is somewhat less intense 

 than that yielded hy salicin under similar conditions. It is con- 

 siderably less soluble than the latter in Avater and in alcohol, and 

 can be removed from aqueous solution not only l>y amylic alcohol 

 (like salicin), l)ut also l)y chloroform and (with difficulty) Ijy 



^ Compare Zvvenger, Annal. d. Chem. und rhariii. xc. 03, ]8;'8 (Amer. 

 Journ. Pharm, xxxiii. ."52'»). 



