450 GUMS 



Varieties. Sennaar gum, Gedaref gum, Ghezireh gum, Talka gum, 

 Somali gum, Aden gum, &c., are varieties of East African gums and 

 are considered inferior to Kordofan gum ; the latter gives a Isevo- 

 rotatory solution, whereas many of the other East African gums 

 give a dextrorotatory solution. 



Senegal gum is exported from the Senegal river to Bordeaux. It 

 is derived from A. Senegal, but may be distinguished from Kordofan 

 gum by being (usually) slightly more coloured, less fissured and by 

 containing vermiform tears. 



Mogadore gum (A. gummifera, Willdenow) ; is mostly dark in 

 colour and but little fissured ; occasional white fissured tears are 

 probably Sudan gums. 



Indian (Acacia) gums include Amrad gum (A. arabica), Amritsar 

 gum (A. modesta), &c. The flora of the deserts of Sind resembles 

 that of the African. The gums are often in large tears, varying in 

 colour from yellow to dark brown, and are used for calico printing, 

 &c. (For ghatti gum see below.) 



Cape gum (A. horrida, Willdenow) and Australian gum (A. deal- 

 bxta, Link ; A. pycnantha, Bentham) find application in various 

 industries. 



Many of these gums form glairy, ropy solutions with water, and when 

 diluted throw down gelatinous deposits of gum that has swelled but 

 not dissolved. An acacia gum suitable for pharmaceutical use should 

 be free from both these characters, and should further give no reaction 

 for starch (which might be present as an adulterant of powdered gum) 

 or for tannin, which is present in certain inferior varieties of gum (such 

 as Australian) ; a 10 per cent, aqueous solution should be slightly 

 laevorotatory (absence of dextrin, from which an artificial gum has 

 been prepared, certain sugars, &c.). 



GHATTI GUM 



(Gummi Indicum) 



Source, &C. Ghatti gum is obtained from Anogeissus lalifolia, 

 Wallich (N.O. Combretacece) , a large tree indigenous to India and 

 Ceylon. 



Description. The gum occurs in vermiform or rounded tears, the 

 best qualities being almost colourless, the inferior yellow to dark brown . 

 The surface is dull and the fracture uniform and glassy, not exhibiting 

 cracks. Its aqueous solution gives only a slight precipitate with 

 solution of lead subacetate (that of acacia gum gives a copious one). 

 With water it forms a nearly colourless mucilage about twice as viscous 

 as that made with the same proportion of acacia. 



