170 GLUCOSIDES OTHER THAN TANNINS. 



a green colour and subsequently yield a yellow precipitate: 

 Fraxin is thrown down by acetate of lead. 1 



Syrincjln ( 55) crystallizes in colourless needles, dissolves with 

 difficulty in cold water, more easily in hot water and alcohol, but 

 is insoluble in ether. Basic acetate of lead does not precipitate it 

 from aqueous solution. Cone, sulphuric acid dissolves it with 

 deep blue colouration ; Frohde's reagent, blood- red passing to- 

 violet ; cone, nitric acid, deep red. Chloroform extracts syringin 

 from aqueous solution. 2 



For globularin see Walz; 3 for coriamyrtin compare 155; for 

 inttosporiu see v. Miiller ; 4 for samaderin see de Yrij. 5 



Colocynthin can be obtained in yellowish crystals which dissolve 

 in cone, sulphuric acid with the gradual production of a fine red 

 colour ; Frohde's reagent produces a cherry-red. It is extremely 

 bitter, easily soluble in water and alcohol, but insoluble in ether. 

 Benzene ( 55), or better, chloroform or amylic alcohol, extracts it 

 from aqueous solution it is precipitated by basic acetate of lead 

 and b}^ tannin. 



Bryonm is also precipitated by the latter reagent. 6 



For ononin, which gradually assumes a cherry-red colour with 

 cone, sulphuric acid, see Hlasiwetz. 7 



Apiin crystallizes in shining silky needles soluble in hot water 

 or, more easily, in hot alcohol. Ether does not dissolve it. 

 Ferrous sulphate colours the aqueous solution blood-red. Both alcoholic 

 and aqueous solutions gelatinize on cooling. In dilute alkalies apiin 

 dissolves with yellow colouration. 



For datiscin, which is also coloured yellow by alkalies, see 

 Braconnot 8 and Stenhouse. 9 Ferric chloride precipitates it green ; 



1 For a number of other glucosides and allied substances (argyraescin, 

 aphrodfescin, etc.) discovered by Rochleder in horse-chestnuts, see Journ. f. 

 pract. Chem. Ixxxvii. 26, 1863 (Amer. Journ. Pharm. xxxv. 290). 



2 For the nearly allied ligustrin, see Kromayer, Archiv d. Pharm. cv. 9, 

 1861 ; for syringopicrin (easily soluble in water), ibid. cix. 26, 1862. 



3 N. Jahrb. f. Pharm. vii. I, 1857 ; xiii. 281, 1860. 



4 ' The Organic Constituents of Plants,' Melbourne, 1878. 



5 Chem. Centralblatt, 92, 1859 ; Jahresb. f. Pharm. 208, 1872. SeeBlume, 

 Amer. Journ. Pharm. xxxi. 342. 



6 N. Jahrb. f. Pharm. ix. 65, 217, 1859 (Amer. Journ. Pharm. xxxi. 249). 

 " Chem. Centralblatt, 449, 470, 1855. 



8 Annales de Chimie et de Physique [2], iii. 277, 1816. 



9 Annal. d. Chem. und Pharm. xcviii. 166, 1856 (Journ. Chem. Soc. ix. 

 226). For helianthic acid compare Ludwig und Kromayer, Archiv d. Pharm. 

 [2], xcix. 1, 1848 (Amer. Journ. Pharm. xxxii. 135). 



