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RESIN (through O.Fr. resine, modern r...

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Originally appearing in Volume V23, Page 183 of the 1911 Encyclopedia Britannica.
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RESIN (through O.Fr. resine,
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modern reline, from
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Lat. resina, prcbably Latinized from Greek Pirivrt, resin)
  , a secretion formed in
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special resin canals or passages of
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plants, from many of which, such as, for example, coniferous trees, it exudes in soft tears, hardening into solid masses in the air . Otherwise it may be obtained by making incisions in the bark or wood of the secreting plant . It can also be extracted from almost all plants by treatment of the tissue with
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alcohol . Certain resins are obtained in a fossilized condition,
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amber being the most notable instance of this class;
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African copal and the kauri gum of New Zealand are also procured in a semi-fossil condition . The resins which are obtained as natural exudations are in general mixtures of different,
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peculiar acids, named the resin acids, which dissolve in alkalis to form resin soaps, from which the resin acids are regenerated by treatment with acids . They are closely related to the
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terpenes, with which they occur in plants and of which they are oxidation products . Examples of resin acids are abietic (sylvic) acid, C,8H28O2, occurring incolophony, and pimaric acid, C2OH3002, a constituent of gallipot resin . Abietic acid can be extracted from colophony by means of hot alcohol; it crystallizes in leaflets, and on oxidation yields trimellitic, isophthalic and terebic acid . Pimaric acid closely resembles abietic acid into which it passes when distilled in a vacuum; it has been supposed to consist of three isomers . Resins when soft are known as oleo-resins, and when containing benzoic or cinnamic acid they are called balsams . Other resinous products are in their natural condition mixed with gum or mucilaginous substances and known as gum-resins . The general conception of a resin is a noncrystalline
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body, insoluble in
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water, mostly soluble in alcohol, essential oils, ether and hot fatty oils, softening and melting under the influence of heat, not capable of sublimation, and burning with a bright but smoky flame .

A typical resin is a transparent or translucent

mass, with a vitreous fracture and a faintly yellow or brown colour, inodorous or having only a slight turpentine odour and taste . Many compound resins, however, from their admixture with essential oils, are possessed of distinct and characteristic odours . The hard transparent resins, such as the copals, dammars, mastic and sandarach, are principally used for varnishes and cement, while the softer odoriferous oleo-resins (
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frankincense, turpentine, copaiba) and gum-resins containing essential oils (ammoniacum, asafoetida, gamboge, myrrh,
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scammony) are more largely used for therapeutic purposes and
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incense . Amber (q.v.) is a fossil resin .

End of Article: RESIN (through O.Fr. resine, modern reline, from Lat. resina, prcbably Latinized from Greek Pirivrt, resin)
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