n good water-colour drawing by these two expedients,
interlacing the colours, or retouching the lower one with fine darker
drawing in an upper. Sponging and washing for dark atmospheric effect is
barbarous, and mere tyro's work, though it is often useful for passages
of delicate atmospheric light.

(_c._) When you have time, practice the production of mixed tints by
interlaced touches of the pure colours out of which they are formed, and
use the process at the parts of your sketches where you wish to get rich
and luscious effects. Study the works of William Hunt, of the Old
Water-colour Society, in this respect, continually, and make frequent
memoranda of the variegations in flowers; not painting the flower
completely, but laying the ground colour of one petal, and painting the
spots on it with studious precision: a series of single petals of
lilies, geraniums, tulips, &c., numbered with proper reference to their
position in the flower, will be interesting to you on many grounds
besides those of art. Be careful to get the _gradated_ distribution of
the spots well followed in the calceolarias, foxgloves, and the like;
and work out the odd, indefinite hues of the spots themselves with
minute grains of pure interlaced colour, otherwise you will never get
their richness of bloom. You will be surprised to find, as you do this,
first the universality of the law of gradation we have so much insisted
upon; secondly, that Nature is just as economical of _her_ fine colours
as I have told you to be of yours. You would think, by the way she
paints, that her colours cost her something enormous: she will only give
you a single pure touch just where the petal turns into light; but down
in the bell all is subdued, and under the petal all is subdued, even in
the showiest flower. What you thought was bright blue is, when you look
close, only dusty grey, or green, or purple, or every colour in the
world at once, only a single gleam or streak of pure blue in the centre
of it. And so with all her colours. Sometimes I have really thought her
miserliness intolerable: in a gentian, for instance, the way she
economises her ultramarine down in the bell is a little too bad.

Next, respecting general tone. I said, just now, that, for the sake of
students, my tax should not be laid on black or on white pigments; but
if you mean to be a colourist, you must lay a tax on them yourselves
when you begin to use true colour; that is to say, you must use t