PLANTS PRODUCING GUMS AND RESINS 319 



Tolu balsam when newly exported is a soft brown resin, scarcely 

 fluid, but not viscous. In the course of time U hardens and eventually 

 becomes brittle. Seen in a thin layer it is perfectly transparent and 

 reddish or yellowish-brown in colour. It has a very agreeable smell,, 

 which somewhat resembles that of benzoin ; its taste is equally 

 aromatic. In very old samples, those, for instance, which were 

 imported into Europe in small calabashes during the last century, the 

 balsam is resinified, brittle, and easily pulverized; the fracture is 

 brilliant and crystalline. This old balsam is of a dark amber colour 

 and has a delicate perfume. 



Tolu balsam is extremely soluble in alcohol and chloroform, less 

 soluble in ether. Its chemical composition is very complex: 7*5 per 

 cent, of an aromatdc oil with an acid reaction composed almost 

 entirely of two esters, benzylbenzoic and benzylcinnamic ester; 12- 15. 

 per cent, of free cinnamic and benzoic acids; a resin which on 

 saponification gives benzoic and cinnamic acids; a resinotannic alcohol, 

 toluresinotannol ; and finally, 0*05 per cent, of vanillin. 



The chief export of this product is from Bolivia. In i8go the 

 value of the Bolivian export was 189,048 piastres (a piastre is worth 

 about 4s.). 



Pterocarpus Marsupium — This member of the group is a tree which 

 is found on the coast of Malabar and in the forests of Vellore,. 

 Travancore, &c. The tree is a very large one, and the inflorescences 

 are in terminal panicles with white flowers slightly tinted with yellow. 

 The external portion of the bark is brown, whilst the interior is yellow 

 and dotted with red spots which mark the canals from which the 

 blood-red liquid escapes and is collected. 



In Roxburgh's work there is a note which runs somewhat as 

 follows : " From incisions made in the bark there escapes a red liquid 

 which hardens on exposure to the air and forms a gum resin of dark 

 red colour and very brittle. When reduced to powder it is brown 

 and sparkling. It burns with difficulty in the flame of a candle; with- 

 out melting or swelling and without emitting any particular odour, 

 it is reduced to a white ash. It melts in the mouth, like all true 

 gums. Its taste is markedly but simply astringent, as much so as 

 the gum of Biitea^ to which it bears considerable resemblance. It 

 is rapidly and almost completely soluble in both water and alcohol. 

 The solution is of a fine dark red colour; the alcoholic solution is 

 perhaps the more striking, but the action of ferric salts points to there 

 being less astringency than dn the aqueous solution. This is one point 

 of contrast with the gum of Biitea, which is less soluble in alcohol, 

 and under the action of ferric salts shows more astringency in an 

 alcohol than in an aqueous solution." 



This gum is known in India as Malabar kino, and to druggists as 

 Amboyna kino. Vauquelin gives the following composition : — 



Tani'in and i-xtrac'ive matters ... ... ... ... 75 



Ueil glim ... ... ... ... ... ... 24 



Insoluble matter ... ... ... ... ... i 



100- 



