harpness and a mild acid.

Hence, interweaving lines and very close lines are bitten more deeply by
the same acid than lines drawn parallel to each other, and widely
spaced, although they may all have been executed with the same needle.
If, in an architectural subject, you have drawn the lines with the same
instrument, but far apart on one side, and closely and crossing each
other on the other, you must not let them all bite the same length of
time, if you wish them to hold the same distance. It will be necessary
to stop out the latter before the former, otherwise you will have a
discordant difference in tone. There will be inequality in the biting,
but it will not be perceptible to the eye, as the general harmony has
been preserved. (See Pl. IV. Fig. 1.)

In short, strong acid rather widens than deepens the lines; mild acid,
on the contrary, eats into the depth of the copper, and produces lines
which are shown in relief on the paper, and are astonishingly powerful
in color. This is especially noticeable in the etchings of Piranesi, who
used hard varnish.

42. =Last Stages of Biting.=--But let us return to our operation. You
noticed that I allowed your plate to bite quite a while; this was
necessary to detach your foreground and middle-ground vigorously from
the sky and the background. You may now stop out the trees, the tower,
and the tent in the middle-ground, and the vertical part of the bridge,
which is in half-tint, and then proceed. Note that the number of bitings
is not fixed, but depends on the effect to be reached.

"In that case it is to be hoped, for the sake of my apprentice hands,
that I shall never have many bitings to do. Just look at my fingers!
They are in a nice state. The prettiest yellow skin you ever saw!"

Oh, don't let that color trouble you; it will be all black by to-morrow.

"Much obliged to you for this bit of consolation!"

Besides, it will take you a week to grow a new skin. In future you must
soak your fingers in pure water whenever you have got them into the
acid. You might have used india-rubber finger-gloves; they are excellent
to keep the hands clean, but it is not worth while to trouble about them
for the present, as we are almost done.[10] I think you may now stop out
all that remains, with the exception of the darkest places in the
foreground, to which we must give a final biting.

There! Now we've got it! Withdraw your plate for the last time, and as
there are some very wide