chromogen
(ˈkrəʊmədʒɛn)
[f. chromo- 2 + -gen.]
(See quots.) spec. in Dyeing, an acid colour used to dye brown.
| 1858 Thudichum Urine 328 The chromogen of indigoferous plants is a peculiar colourless substance. 1879 Watts Dict. Chem. VIII. i. 696 The compound which requires only the presence of a salt-forming group to convert it into a dye-stuff may be called a chromogen (thus NO2 is the chromophore of nitraniline and nitrophenol, and nitrobenzene is their chromogen). 1882 Syd. Soc. Lex., Chromogen, a former term for a supposed vegetable colouring matter which is acted upon by acids and alkalis in producing red, yellow, or greeen tints. 1892 Dyer 20 June 92/2 Chromogen may even be used with other dyestuffs to obtain a variety of useful shades of brown. 1910 Encycl. Brit. VIII. 746/1 Other acid colours, e.g. Chromotrope, Chrome Brown, Chromogen, Alizarin Yellow, &c. 1961 Blackshaw & Brightman Dict. Dyeing 43 Chromogen, the whole atomic grouping of which the Chromophore and the Auxochrome(s) are a part. |
Hence chromoˈgenic a.
| 1884 E. E. Klein Micro-Org. & Dis. vii. 41 Chromogenic micrococci..are characterised by their power of forming pigment of various colours. 1901 Lancet 6 July 41/1 Organic colourings..may be the product of certain species of bacteria. Hence they are called chromogenic bacteria. 1913 W. Bateson Mendel's Princ. Hered. viii. 142 All that is common to them [sc. albinos] is the absence of colour, i.e...of the chromogenic substance. |