CAOUTCHOUC. 



731 



gum-resin, from Pterocarpus ^^arsupium, from India and 

 Ceylon, contains 75 per cent, of tannic acid. 



Dammar, or copal, is a gum-resin used in making varnish. 

 The finest transparent dammar comes from Dammara orientalis, 

 the Amboyna pine, growing in the Molluccas ; D. australis 

 (New Zealand) also yields dammar, so does Valeria indica, a 

 large tree of the Indian Peninsula, its dammar being white 

 and valuable. Common dammar comes from Ayathits lorauthi- 

 folia, a conifer growing in Borneo and the other large islands 

 of the Indian Ocean. 



Lac is a resinous incrustation on the twigs of various 

 Indian trees produced by a minute hemipterous insect, 

 Tachardia Lacca. This substance contains a crimson dye, 

 known as lac-dye ; also shellac, used in making varnishes, 

 cements, sealing-wax, lacquer work, lithographic ink, gramo- 

 phone records, etc. For a full account of the method of 

 production of lac, the reader is referred to Troup's "Indian 

 Forest Utilisation." 



Elastic gums include the valuable products, caoutchouc, or 

 rubber, gutta-percha and balata. 



Caoutchouc* is the produce of various trees, shrubs and 

 climbers, growing generally within 250 miles north, or south, 

 of the equator, usually with an annual rainfall averaging 

 80 inches, but in the Congo not exceeding 40 inches ; the 

 following are the chief species that yield caoutchouc : 



* " India-rubber and its Manufactures," with chapters on gutta-percha and 

 balata. 11. I.. Terry. Constable & Co., London. 1 ( J07. 



