68 ON COLOUK. Part I. 



will show the character I ascribe to each. All we require is 

 that it should he fixed ; and I shall have occasion to notice 

 the names applied to them, in mentioning "Werner's Nomen- 

 clature of Colours." (See below, p. 91.) 



There is, indeed, great uncertainty respecting the exact 

 complexion of most colours in other languages as well as in 

 our own. What, for instance, can be more indefinite than 

 the name of purple, the tones of which vary according as they 

 contain more red or more blue ? What again do we under- 

 stand by the name " violet colour ? " Some consider it to be 

 composed of equal parts of one kind of red and blue ; others, 

 to be that of the violet flower, though the name is as indefinite 

 as the colour of the flower itself ; all which tends to show how 

 necessary it is to define the nature of each colour, and of the 

 hue of which we speak ; and how uncertain must be the im- 

 pression conveyed by the name of any one, unless we determine 

 the sense in which we use it. Again, in other purples, the 

 porphyry has more red, the lilac more blue ; and we must dis- 

 tinguish the various sub-tones as well as tones, by qualifying 

 them as red-lilacs or blue-lilacs; red-violets . or blue-violets, 

 &c, as by other specifications of their different intensities. 

 Of the imperial purple I shall speak presently. Similar 

 gradations exist in orange and in green; according to the 

 greater proportion of red and yellow in the former, and of 

 blue and yellow in the latter. The claim of these three to be 

 secondary colours is their being each composed of two only of 

 the primaries, and to their being in the prism ; and browns 

 and greys, ranked with them by Hundertpfund and some 

 others, can only hold a place in a distinct class. 



The prismatic colours dissolve so insensibly into each 

 other, and form a succession of hues so finely graduated, that 

 it is not possible to perceive the exact limit of each * ; but in 



* In the rainbow and the prism red and violet are the two outermost 

 colours ; and " the red shades off by imperceptible gradations into orange, 



