tter of curiosity, but with reserve. It is better to use the dry
point, which has more affinity to the processes natural to etching.

[Illustration: Plate V.]

78. =Mottled Tints.=--You may also make use of the following process
(but with the same restrictions) in the representation of parts of old
walls, of rocks and earth, or of passages to which you desire to impart
the character of a sort of artistic disorder:--Distribute a quantity of
ordinary etching-ground on a copper plate sufficiently heated; then take
your dabber, and, having charged it unequally with varnish, and having
also heated your etched plate, press the dabber on the passages which
are to receive the tint; the varnish adheres to the plate in an
irregular manner, leaving the copper bare here and there. Now stop out
with the brush those parts which you desire to protect, and bite in with
pure acid; the result will be a curiously mottled irregular tint (see
Pl. V. Fig. 2). Properly used in the representation of subjects on which
you are at liberty to exercise your fancy, this process will give you
unexpected and often happy results.

79. =Stopping-out before all Biting.=--Before we proceed, I must show
you an easy method of representing a thunder-storm (see Pl. V. Fig.
2):--Work the sky with the needle, very closely, so as to get the sombre
tints of the clouds; and, before biting, trace the streaks of lightning
on the etched work with a brush and stopping-out varnish; being thus
protected against the acid, these streaks will show white in the
printing, and the effect will be neater and more natural than if you had
attempted to obtain it by the needle itself, as you will avoid the
somewhat hard outlines on either side of the lightning, which would
otherwise have been necessary to indicate it.

You can employ the same process for effects of moonlight, for reflected
lights on water, and, in fact, for all light lines which it is difficult
to pick out on a dark ground.

B. ZINK PLATES AND STEEL PLATES.

80. =Zink Plates.=--So far I have spoken to you of copper plates only;
but etchings are also executed on zink and on steel. Zink bites rapidly,
and needs only one quarter of the time necessary for copper, with the
same strength of acid; or, with the same length of time, an acid of ten
degrees is sufficient. The biting is coarse, and without either delicacy
or depth. A zink plate prints only a small edition.[18]

81. =Steel Plates.=--Steel also bites wi