TROPICAL AGRICULTURIST 



AND 



MAGAZINE OF THE 



CEYLON AGRICULTURAL SOCIETY. 



Vol. XXXV. COLOMBO, NOVEMBER 15th, 1910, No. 5. 



GUMS AND RESINS. 



Samples of gums, collected from trees 

 native or cultivated in Ceylon, are otten 

 sent to us with a request to know 

 whether it is woi'th while collecting them 

 for sale. In general we may say at once 

 that there is no gum in Ceylon worth 

 collecting for any but immediately local 

 or personal use. 



Gums result from the disintegration of 

 the internal tissues of plants, and are 

 especially commonly found in dry 

 climates. In a wet country, like Ceylon, 

 they are usually, to a considerable 

 extent, washed off the trees by the rain, 

 a fact which reduces the yield, besides 

 removing the most valuable part of it. 



The standard gum of the market is 

 gum-arabic, the product of Acacia 

 Senegal and other Soudanese species. 

 The gum is described as exuding from 

 the branches principally during the pre- 

 valence of the dry desert winds from the 

 north and east which blow in the winter 

 after the rainy season. None of the 

 other Acacias yield so good a gum as 

 A. Senegal. The gum of this species is 

 almost pure arabin, which is fully soluble 

 in water In other species, including 

 those grown upcountry in Ceylon, the 

 arabin is mixed with a larger or smaller 

 quantity of insoluble matter, so that 



considerable expense is involved in 

 purifying it. As the value of even the 

 best African gum-arabic is only 33s. per 

 cwt., while the inferior East Indian is 

 worth but 18s., there is not money 

 enough in it to admit of purification. It 

 takes a good deal of gum to make a 

 hundredweight. 



Another class of gums is composed of 

 bassorin, and of these the standard is 

 gum-tragacanth, derived from Astra- 

 galus gummijer of the Mediterranean 

 Coasts. We have not, so far as known, 

 any species here yielding such gum in 

 the pure state. 



Taking it altogether, it is safe to say 

 that we have no good gums worth 

 collecting in this country. With resins, 

 often confused with gums, a somewhat 

 different story may be told. Resins are 

 also collected from natural exudations, 

 or more commonly from wounds made 

 in the bark. Resins are insoluble in 

 water, but dissolve in alcohol or ether, 

 and burn with a sooty flame. Their 

 chief use is in the manufacture of 

 varnish. 



Several of our Dipterocarp trees, such 

 as the doou, the piniberaliya, honda- 

 beraliya, &c, yield good resins, as does 

 also the hal, and from some of these local 

 varnishes might be made, in fact are 

 occasionally made. 



