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 ?
After which, the samples were stained with Giemsa and mounted with Canada balsam.
Slide-mounting of lice: a detailed description of the Canada Balsam technique.
Adults were mounted in Canada balsam for identification using the procedures in Wirth & Marston (1968) and the keys in Hoddle et al.
The only specimen available for study, was dissected in 80% ethyl alcohol, and its parts (head, right legs and wings, and genitalia), were mounted on a slide in Canada balsam. Before dissecting, the specimen was placed in 80% ethyl alcohol under a dissecting microscope illuminated with white, cold light at 80X to record coloration.

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