Gums and Resins 



349 



quantities have been exported during the last sixty years. The resin originally exuded from 

 the Kauri pine (Dammara Australis), forests of which still exist in New Zealand from which 

 " fresh kauri " is collected to a small extent. 



Oleo-Resins 



Turpentines. By " turpentine " is usually understood in this country the familiar colour- 

 less liquid used for many domestic purposes. This product is more accurately called " oil 

 of turpentine " since it is produced by the distillation of the crude " turpentine," which exudes 

 from pine trees. " Turpentine " is chiefly obtained from Pinus australis in the United States, 

 Pinus pinaster (maritima) in the Gironde district of France, and Pinus sylvestris in Russia. 

 In the United States preparations for the collection of " turpentine "•■ are made in winter. 

 Three pocket-like cavities, each capable of holding about a quart, are cut in the trees at a 

 distance of 6 to 12 inches above the ground. The " turpentine " which exudes from incisions 

 periodically made in the tree accumulates in these cavities, and is ladled out from time to time 

 by the collectors. Some of the turpentine dries on the trees ; this is scraped off and forms 

 the material known in com- 

 merce as ''common frank- p 

 incense." The "turpentine" 

 is then transported to central 

 factories for distillation, the 

 distillate being \ oil of 

 turpentine " and the resi- 

 due " common rosin " or 

 " colophony." 



TANS AND DYES 



The operation of "tanning" 

 consists in the conversion of 

 hides and skins into leather. 

 This change is effected by 

 the use of certain vegetable 

 products called tanning- 

 materials, which contain a 

 peculiar compound known 

 as tannin, having the prop- 

 erty of combining with the 

 substance of hide and skin 

 forming leather, thereby con- 

 verting a material which 

 readily decays into one which 

 is proverbially resistant. 



Nature of Tanning 

 Materials 



Tannin occurs in all parts 

 of plants, but it appears to 

 be most secreted in those 

 portions which are of rela- 

 tively little use to the plant 

 as a living agent, viz., the 



HEMLOCK SPRUCE 



