Canada balsam


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Canada balsam,

yellow, oily, resinous exudation obtained from the balsam firbalsam fir,
common name for the evergreen tree Abies balsamea of NE North American boreal forests. It has small needles and cones and is used for lumber. It is also called Canada balsam, as is the resin it produces, which is used as an adhesive in optical lenses and glass
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. It is an oleoresin (see resinresin,
any of a class of amorphous solids or semisolids. Resins are found in nature and are chiefly of vegetable origin. They are typically light yellow to dark brown in color; tasteless; odorless or faintly aromatic; translucent or transparent; brittle, fracturing like glass;
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) with a pleasant odor but a biting taste. It is a turpentineturpentine,
yellow to brown semifluid oleoresin exuded from the sapwood of pines, firs, and other conifers. It is made up of two principal components, an essential oil and a type of resin that is called rosin.
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 rather than a true balsam. On standing, the essential oil in Canada balsam evaporates, leaving behind the resin as a hard, transparent varnish. Canada balsam is valued as an optical mounting cement, e.g., for lenses and microscope slides, since it yields, when dissolved in an equal volume of xylene, a noncrystallizing cement with a refractive index nearly equal to that of ordinary glass. It is used also in paints and polishes.

Canada balsam

[‚kan·ə·də ′bȯl·səm]
(materials)
A transparent balsam useful for cementing together lenses and other optical elements because its index of refraction is in the same range as that of glass.
References in periodicals archive ?
A piece of worm colonies of each species with the size of 10 mm x 10 mm was then oriented and mounted in Canada balsam for grinding.
After photographing the specimen, small pieces of dermal and atrial surfaces were wholemounted in Canada balsam for light microscopy and digested in hot nitric acid for spicule cleaning.

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