WIXTERGREEX. 343 



the acid sulptiites of the alkali metals,* this property being 

 made use of in its purification. As a phenol it forms salts, ethers 

 and ethereal salts. 



When salicyl aldehyde is agitated with strong aqueous ammonia 

 at a gentle heat, the salicyl ite of ammonium is formed, and 

 crystallises on cooling in yellow needles. This body is slightly 

 soluble in water and still less in alcohol. It melts at 115" C, and 

 volatilises at a higher temperature without alteration. When kept 

 in the moist state in a closed vessel it gradually decomposes, 

 blackens, becomes semi-fluid, gives off ammonia and acquires a 

 " very penetrating odour of roses." 



Salicin, C^g H-^g 0-, is the glucoside which constitutes the 

 bitter principle of the leaves and bark of the willow. It was at 

 first considered to be an alkaloid, but on being subjected to careful 

 investigation by Piria, a complete explanation of its nature was 

 arrived at.f 



It occurs in the bark, leaves and female flowers of many trees 

 which do not all belong to the willow tribe. It has been found to 

 the extent of 4 per cent, in sctlix helix, pentandra, and prcecox ; has 

 also been found in the bark and leaves of the Poplar :|: ; in the 

 flower-buds of Spircea Ulmaria as above described, and in 

 Castoreum.§ Its occurrence in castoreum is explained by the 

 fact that when taken internally a portion of it appears in the 

 urine as saligenin, salicyl aldehyde and salicylic acid, the remainder 

 being excreted unchanged, and the Castor Beaver feeds on plants 

 which contain it.jl^ 



Besides its other uses, salicin is used for adulterating quinine. 



Salicin can be prepared in the following way : — 3 parts of 

 chopped willow bark are exhausted three times with boiling water 



* Ann. Chem. Pliarm., Ixxxv., p. 93. 



t Ann. Chem. Phann., xxx., pp. 151 and 189 ; Ivi., p. 49 ; also Liebig, 

 ibid., XXX., p. 185. 



I Braconnet in Ann. Cliim. Pliys., xliv., p. 296, and Tischausen, Ann. 

 Chem. Pharm., vii., p. 280. 



§ Ibid., Ixvii., p. 360. 



il Laveron and Millon, Ann. Chem. Pharm., lii., p. 435, and Ranke, 

 Jahresb. Chem., 1852, p. 711. 



fl It is remarkable that the odour of Castoreum is noticeable in the 

 Ferment oil of Salix pentandra, a willow common in the North of England. 

 See "Ferment oils." 



