RESINS 



Resins and gums are products obtained from the exudations 

 of plants. The products may exude spontaneously, but are more 

 often secured by making incisions in the bark or trunk. It 

 is somewhat difficult to draw a sharp distinction between gums 

 and resins, as there are a number of plant exudations known as 

 oleoresins, balsams and gum resins which have properties in- 

 termediate between those of true gums and resins. In general, 

 plant products of this nature contain resins, gums, volatile oils, 

 and aromatic acids. Allen * gives a very satisfactory discussion 

 of resins and the methods used in analyzing them. 



Resins are solid or semi-solid and are usually insoluble in 

 water, but soluble in alcohol, ether, and volatile oils. They are 

 formed usually by the spontaneous evaporation of resinous 

 juices which exude naturally from the trunks of trees or when 

 the trunks are cut. Frequently resins may be extracted from 

 various parts of plants by solvents such as alcohol and ether. 

 They are also found as minerals (mineral resin) which are, no 

 doubt, products of extinct vegetation. Resins from different 

 sources frequently show great differences in their chemical com- 

 position and properties. Commercially, Manila copal, which is 

 used in making varnishes, is the most important Philippine resin. 



Oleoresins are the plant exudations consisting of resins dis- 

 solved in volatile essential oils. Manila elemi, employed in var- 

 nish making, and turpentine are examples of this class of sub- 

 stances occurring in the Philippines. 



Gum resins are plant exudations, like gamboge, which consist 

 of a mixture of resin and gum. Gamboge of an inferior quality 

 can be obtained in the Philippines from Gdrcinia veyiulosa and 

 probably from other species of Garcinia. 



Certain of the dipterocarp resins can be collected in large 

 quantities and appear to offer commercial possibilities as ma- 

 terials for the manufacture of varnishes. 



Family PINACEAE 



Genus AGATHIS 



AGATHIS ALBA (Lam.) Foxw. (Figs. 2-4). Almaciga. 



Local names: Adictngau (Camarines) ; aUnsago (Benguet) ; almaciga 



(Mindoro, Lepanto, Bataan, Tayabas, Benguet, Zambales, Palawan, Cama- 



* Allen, Commercial organic analysis, Volume 4 (1911), page 1. 

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