100 AROMATIC COMPOUNDS AND - [GEL 



water extract as in Expt. 101 (c)-(i). Also take equal quantities of the water extract 

 in two evaporating dishes. To one add sodium chloride. Note (as mentioned above, 

 see p. 98) that the colour fades less rapidly from the extract containing the salt. The 

 ..flowers of the following species can be used ": blue Larkspur (Delphinium), Cornflower 

 (Centaurea Cyanus], blue Columbine (Aquilegia). 



There is a small group of plants belonging to some allied natural 

 orders, of which the anthocyan pigments give chemical reactions still 

 more different from the general type already described, though they 

 nevertheless resemble each other. Such, for instance, are the pigments 

 of various genera of the Chenopodiaceae [Beet (Beta), Orache (Atriplex)^ 

 Amarantaceae (Amaranthus and other genera), Phytolaccaceae (Phyto- 

 lacca) and Portulacaceae (Portulaca). These anthocyan pigments are 

 insoluble in alcohol but soluble in water : they give a violet colour with 

 acids, red to yellow with alkalies, and a red precipitate with basic lead 

 acetate. 



Expt. 103. Reactions of the Beet-root (Beta vulgaris) pigment. Take some Beet- 

 root leaves, tear them into small pieces and put them into alcohol. Allow the leaves 

 to stand for some time and note that the chlorophyll is extracted but the red pigment 

 is insoluble. Then pour off" the alcohol and add water : the red pigment goes into 

 solution. Filter off the solution and make the following tests : 



(a) Add acid. The pigment turns violet. 



(b) Add alkali. The pigment becomes redder and finally turns yellow. 



(c) Add basic lead acetate. A red precipitate is formed. 



(d) Acidify with hydrochloric acid and add zinc dust. The colour disappears, but 

 on filtering off from the zinc it does not return again. 



Anthocyan pigments may also occur in leaves, and this is veiy obvious 

 in red-leaved varieties of various species such as the Copper Beech, the 

 Red-leaved Hazel, etc. 



Expt. 104. Extraction of anthocyan pigment from the Red-leaved Hazel. Extract 

 some leaves of the Blood Hazel (Corylus Avellana var. rubra) with alcohol. Filter off 

 and evaporate the solution to dryness. Add water. Pour a little of the crude mixture 

 in the dish into a test-tube and add ether. There will be a separation into a green 

 ethereal layer containing chlorophyll, and a lower water layer containing anthocyan 

 pigment. Filter the extract remaining in the dish and with the filtrate make the 

 tests already given in Expt. 101 (c)-(i). 



The leaves of the Copper Beech (Fagus sylvatica var. purpurea) can also be used. 



In many flowers, the cells of the corolla may contain yellow plastid 

 (see p. 39) in addition to anthocyan pigments. The colour of the petals 

 is in these cases the result of the combination of the two, and is usually 

 some shade of brown, crimson or orange-red, as in the brown-flowered 

 variety of Wallflower (CheirantJius Clieiri). 



