PYROGALLOL, or PYROGALLIC ACID

This article appears in Volume V22, Page 693 of the Encyclopedia Britannica.

Encyclopedia Britannica - Main :: PRE-PYR

PYROGALLOL, or PYROGALLIC ACID , a trioxybenzene, C6H3(OH)3 (1 : 2 : 3), prepared by Scheele in 1786 by

heating

HEATING

gallic acid, C6H2(OH)3CO2H. It is also obtained by

heating

HEATING

para-chlorphenoldisulphonic acid with potassium hydroxide.
It forms white plates, melting at 132, readily soluble in water, and subliming without decomposition. It is an energetic reducing agent, a property utilized in its application in gas

analysis

ANALYSIS (Gr. avci and Meta, to break up into parts)

to absorb oxygen, and in photography (q.v.) as a developer. The aqueous solution is turned bluish black by ferrous sulphate containing a ferric salt. It does not combine with

hydroxylamine

HYDROXYLAMINE, NH2OH

, as does the isomeric phloroglucin which yields a trioxime(see POLYMETnYLENES). Pyrogallol dimethyl ether is found in beechwood tar. Pyrogallol has antiseptic properties and is employed medicinally in the treatment of psoriasis. Eugallol, or monacetyl pyrogallol and lenigallel, or triacetyl pyrogallol, are also used.
position of various rocks, for example, limestone. That it is readily deposited from solution is shown by the frequent occurrence of black dendritic markings in the crevices of rocks, excellent examples of which are seen in mocha stone (q.v.) and in the lithographic stone of Solenhofen in Bavaria. It is deposited from the waters of some springs, and manganiferous nodules are dredged from the floor of the deep sea.
As an ore it is extensively

mined

MINED

Ilmenau

ILMENAU

and several other places in Thuringia, at Vorderehrensdorf near Prossnitz in Moravia, Platten in Bohemia, in North Wales, at several places in the United States (

Vermont

VERMONT

, Virginia, Arkansas, &c.), Nova Scotia and Brazil. Pyrolusite, together with the rather less important ore, psilomelane, has various economic applications. It is extensively used for the manufacture of spiegeleisen and ferromanganese, and of various

alloys

ALLOYS (through the Fr. aloyer, from Lat. alligare, to combine)

, such as

manganese

MANGANESE (symbol Mn; atomic weight, 54.93 (0=16)], a metallic chemical element. Its dioxide (pyrolusite)

-bronze. As an oxidizing agent it is used in the preparation of chlorine and disinfectants (permanganates), and for decolorizing glass: when mixed with molten glass it oxidizes the ferrous iron to ferric iron, and so discharges the green and brown tints, hence the name pyrolusite, from Gr. 7-up (fire) and abiv (to

wash

WASH, THE

). As a colouring material, it is used in calico printing and dyeing; for imparting violet, amber and black colours to glass, pottery and bricks; and in the manufacture of green and violet paints. (L. J. S.)

End of Article: PYROGALLOL, or PYROGALLIC ACID

If you wish, you can link directly to this article.

<a href="http://jcsm.org/StudyCenter/Encyclopedia/PRE_PYR/PYROGALLOL_or_PYROGALLIC_ACID.html">
PYROGALLOL, or PYROGALLIC ACID
</a>

(Previous)
PYROCATECHIN, or PYROCATECHOL

(Next)
PYROGALLOL, or PYROGALLIC ACID

JCSM was founded in 1997 and exists to help the community and bring people into a life-changing and productive relationship with Jesus Christ. JCSM offers over 200,000 free web pages, including its weekly inspirational emails that were sent continuously for over a decade.

Jesus Christ Saves Ministries
P.O. Box 9297
San Diego, CA 92169
1-888-887-0417 or Email