330 PLANTS PRODUCING GUMS AND RESINS 



considers this is another example of how climate can influence the 

 composition and properties of gums. 



Acacia pycnantha. — An Australian acacia cultivated in Algeria 

 and introduced into New Caledonia. It yields a gum of inferior 

 ciuality. The gum is entirely soluble in cold water, but the mucilage 

 is thin and has no adhesive properties whatsoever. 



Acacia homaiophylia — De Cordemoy, in his book " Gommes et 

 Resines," says this acacia yields throughout the summer a large 

 quantity of gum with a striking resemblance to pine resin. It is of 

 a lightish colour and has a brilliant conchoidal fracture. It is 

 soluble in water, makes a pretty, pale-coloured solution, and is 

 perfectly adhesive. 



Acacia pendula. — The gum obtained from this plant is completely 

 soluble in cold water, and gives a light-coloured or rather darker 

 mucilage according to its age. Large quantities are exported from 

 Australia to England. 



Acacia horrida. — In Southern Africa this acacia is exploited by 

 Germans and produces a fair quantity of good quality gum. 



Other gummiferous acacias to be recorded are : In Senegal, Acacia 

 astrmgejis, A. Neboiieb; in Mauritania, A. gunimifera; in East Africa, 

 A. Seyal, A. Ehrenherg'ii; in Australia, A. melanoxylonj A. mollis- 

 simaj A. sofhoras, &c. 



Adenanthera pavonina. — This tree produces the gum known as 

 7nadatta. 



Albizzia Lebbek, — A large tree, of which the common name in 

 Mauritius, Reunion, and the West Indies is Bois noir (black wood). It 

 exudes a gum which Roxburgh records as being of great purity, and 

 in India it is also regarded as a high-class product. 



Baden-Powell says that it is partially soluble in water and swells 

 up in this liquid, tending to form a jelly. 



De Cordemoy has examined samples from Reunion and is of the 

 same opinion. The gum is either reddish and opaque, or pale yellow, 

 limpid, and transparent; it occurs in mammillated fragments, and 

 sometimes in long adhering tears. 



When the product is dried for an hour at 120° C. it loses 6'os per 

 cent, of hygroscopic water; 20 grm. of gum dried in this way are 

 immersed in 400 grm. of distilled water. It then swells up slowly. 

 In 24 hours' time it has considerably increased in volume and forms 

 a reddish translucent mass of granular appearance (de Cordemoy). 

 It can be rendered soluble either by the action of heat in presence of 

 a small quantity of potash, or by the action of heat under pressure. 

 After these modifications it becomes adhesive. 



Albizzia procera. — Both in India and Australia this gum may be 

 gathered in abundance. It is more or less dark in colour, so that 

 pieces are selected in which the dark tint is only superficial. It swells 

 up in water, and is only partially soluble. 



