Definition of Congo red

1. Noun. A red-brown azo dye especially as a chemical pH indicator (congo red is red in basic and blue in acidic solutions).

Category relationships: Solution
Generic synonyms: Acid-base Indicator, Azo Dye

Definition of Congo red

1. Noun. a dye that turns red in alkaline, blue in acidic solutions. ¹

¹ Source:

Medical Definition of Congo red

1. An odourless, dark red or reddish brown powder which decomposes on exposure to acid fumes. It is used as a diagnostic aid in amyloidosis, and has been used as an antihemolytic and detoxicant. Pharmacological action: dyes. Chemical name: 1-Naphthalenesulfonic acid, 3,3'-((1,1'-biphenyl)-4,4'-diylbis(azo))bis(4-amino-, disodium salt (12 Dec 1998)

Congo Red Pictures

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Lexicographical Neighbors of Congo Red

congo copal
congo eel
congo gum
congo red (current term)
congo snake
congoo mallee
congophilic angiopathy
congou tea

Literary usage of Congo red

Below you will find example usage of this term as found in modern and/or classical literature:

1. A System of Physical Chemistry by William Cudmore McCullagh Lewis, James Rice (1920)
"273 58-5 Now the osmotic pressure at 17° C. of the congo red solution present ... congo red, would amount to 290 mm. mercury. Hence the approximately N/r2 ..."

2. A Dictionary of Applied Chemistry by Thomas Edward Thorpe (1921)
"congo red (Lev.) (A.) (By!) (L.) (KS) (BK) (Sch.) (Marden, Orth, and Hastings Corporation) ; congo red R (H.) ; Cosmos Red (B.) ; Cotton Red cone. ..."

3. Principles of Dyeing by George Stronach Fraps (1903)
"congo red is a red-brown powder, readily soluble in water. Its solubility is decreased by the presence of ... Dissolve a little congo red in 200 cc. water. ..."

4. American Druggist (1887)
"We have already noticed Congo-red and it« application as a reagent for acids and ... The first sample of Congo-red ever brought to this country reached us ..."

5. An Introduction to the Study of the Compounds of Carbon, Or, Organic Chemistry by Ira Remsen (1922)
"benzidine, is a dimethyl derivative of congo red containing a methyl group attached to each of the benzene residues of the diphenyl group. ..."

6. Clinical Diagnosis: The Bacteriological, Chemical, and Microscopical by Rudolf Jaksch von Wartenhorst (1899)
"The efficiency of the test is undoubted, and, notwithstanding that its use is subject to certain fallacies,52 the Congo-red test-papers must be classed with ..."

7. The Pharmacopoeia of the United States of America: (The United States by United States Pharmacopoeial Convention (1820)
"Concentrated sulphuric acid dissolves congo red with a slate blue color and, ... congo red Test Solution.—Dissolve 0.5 Gm. of congo red in 90 mils of ..."

8. The American Naturalist by American Society of Naturalists, Essex Institute (1896)
"And that congo red changes to blue in presence of free acid only. It is apparent that the diminution of acid in a digestive vacuole is at first due to a ..."

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