GUMMI ACACIA. 233 



South Canara. The natives extract the oleo-resin in exactly the same 

 method as that followed by the aborigines of Brazil in the case of 

 copaiba, — that is to say, they make a deep notch reaching to the heart 

 of the trunk, from which after a time it flows out. 



This oleo-resin, which has the smell and taste of copaiba, but a much 

 darker colour, was fii-st examined by one of us in 1865, having been 

 sent from the India Museum as a sample of Wood Oil; it was sub- 

 quently forwarded to us in moi-e ample quantity by Dr. Bidie of 

 Madras. It is a thick, viscid fluid, which, owing to its intense tint, 

 looks black when seen in bulk by reflected light ; yet it is perfectly 

 transparent. Viewed in a thin layer by transmitted light, it is light 

 yellmvish-green, in a thick layer vinoua-red, — hence is dichromic. It 

 is not fluorescent, nor is it gelatinized or rendered turbid by being 

 heated to 130° C, thus differing from Wood Oil.^ Broughton " obtained 

 by prolonged distillation with water an essential oil to the extent of 

 25 per cent, from an old specimen, and of moi'e than 40 per cent., from 

 one recently collected. The oil was found to have the same composi- 

 tion as that of copaiba, to boil at 225° C, and to rotate the plane of 

 polarization to the left. The resin* is probably of two kinds, of which 

 one at least possesses acid properties. Broughton made many 

 attempts, but without success, to obtain from the resin crystals of 

 copaivic acid. 



The balsam of Hardiuickia has been used in India for gonorrhoea, 

 and with as much success as copaiba. 



GUMMI ACACIiE. 



Gummi Arahicurn ; Gum Arabic; F. Gomrne Arabique ; G. 

 Arabisches Gummi, Aeacien-Gummi, Kardofan Gummi. 



Botanical Origin — Among the plants abounding in mucilage, 

 numerous Acacise of various countries are in the first line. The species 

 particularly known for aftbrding the largest quantities of the finest gum 

 arable is Acacia Senegal* Willdenow (syn. Mimosa Senegal L., A. 

 Verek Guillemin et Perrottet), a small tree not higher than 20 feet, 

 growing abundantly on sandy soils in Western Africa, chiefly north of 

 the river Senegal, where it constitutes extensive forests. It is called 

 by the negroes Verek. The same tree is likewise found in Southern 

 Nubia, Kordofan, and in the region of the Atbara in Eastern Africa, 

 where it is known as Hashah. It has a greyish bark, the inner layers 



^ It maj' be further distinguished from Oleo-resm of Hardwichia — ^Xo percept- 

 Wood Oil as well as from copaiba, if tested ible alteration ; the mixture pale greenish 

 in the folio wing simple manner: — Put into yellow. 



a tube 19 drops of bisulphide of carbon and By this test the presence in copaiba of 



one drop of the oleo-resin, and shake them one-eighth of its volume of Wood Oil may 



together. Then add one drop of a mixture be easily shown, 



of equal parts of strong sulphnx-ic and ^Beddome, oj}. cit. 



nitric (i -42) acids. Alter a little agitation ^ See also Hazlett, Madras Monthly 



the appearance of the respective mixtures Journ. of Med. Science, June 1872. 



will be as follows : — * Figures in Guillemin and Perrottet 



Copaiha — Colour faint reddish brown, Flora- Senegamb. tent. 1830, p. 246, tab. 



with deposit of resin on sides of tube. 56 ; also Bentley and Trimen, Med. Plants, 



Wood Oil — Colour intense purplish-red, part 17 (1877). 

 becoming violet after some minutes. 



