870 SALICIN. 



process also assists as a decolorising agent. The barks which 

 contain much salicin yield it at once in crystals, when they are 

 exhausted by cold water and the extract evaporated with cau- 

 tion, according to Merck. 



Salicin crystallizes in delicate colourless needles of a silky 

 lustre, which have a bitter taste, and no action on vegetable 

 colours. It is persistent in air, loses nothing at 212, fuses at 

 248, and is decomposed by a higher temperature. Salicin is 

 soluble in 5 or 6* times its weight of cold water, in much less 

 boiling water, is very soluble in alcohol, but insoluble in ether 

 and oil of turpentine. It dissolves purple red in concentrated 

 sulphuric acid, a property by which it may be recognised even 

 in the dry bark, the latter being stained red by sulphuric acid 

 when it contains salicin. 



Salicin does not combine with acids, nor possess alkaline pro- 

 perties. It is thrown down by the ammoniacal acetate of lead 

 as a white precipitate, in which according to Piria 6 atoms of 

 water belonging to salicin are replaced by 6 atoms of oxide of 

 lead ; but according to Ettling, the quantity of oxide of lead is 

 not constant but increases with the washings to which the 

 precipitate is submitted. 



SaUretin, C 30 H 15 O 7 + HO. When raised to the boiling point 

 with dilute sulphuric or hydrochloric acid, the solution of salicin 

 soon becomes turbid, and allows a yellowish substance to fall 

 having the consistence of a resin, which is saliretin. When 

 prepared with concentrated acids, the product wants the atom 

 of water represented in the formula, or is anhydrous. In this 

 decomposition 1 atom of hydrated salicin is resolved into 1 atom 

 of saliretin and 1 atom of grape sugar, which last is found in 

 solution. 



Saliretin is insoluble in water, and precipitated by that liquid 

 from its solution in alcohol, in ether or concentrated acetic acid, 

 in all of which it is very soluble. It is not soluble in ammonia, 

 but is dissolved by the fixed alkalies and precipitated from them 

 by acids. Saliretin is coloured blood-red by concentrated sul- 

 phuric acid ; by nitric acid it is converted into carbazotic acid. 

 (Piria). 



Chorinated salicin, chlorosalicin. Two compounds have been 

 obtained by treating a solution of salicin by chlorine, one a 



