ole expression past recognition.

Try this on simple terms:--

Do a face on white glass in strong outline only: step back, and the face
goes to nothing; strengthen the outline till the forms are quite
monstrous--the outline of the nose as broad as the bridge of it--still,
at a given distance, it goes to nothing; the expression varies every
step back you take. But now, take a matting brush, with a film so thin
that it is hardly more than dirty water; put it on the back of the glass
(so as not to wash up your outline); badger it flat, so as just to dim
the glass less than "ground glass" is dimmed;--and you will find your
outline look almost the same at each distance. It is the pure light that
plays tricks, and it will play them through a pinhole.

And now, finally, let us say that you may do anything you _can_ do in
the painting of glass, so long as you do not lay the colour on too
thick. The outline-touches should be flat upon the glass, and above all
things should not be laid on so wet, or laid on so thick, that the
pigment forms into a "drop" at the end of the touch; for this drop, and
all pigment that is thick upon the glass like that, will "fry" when it
is put into the kiln: that is to say, being so thick, and standing so
far from the surface of the glass, it will fire separately from the
glass itself and stand as a separate crust above it, and this will
perish.

Plate IX. shows the appearance of the bubbles or blisters in a bit of
work that has fried, as seen under a microscope of 20 diameters; and if
you are inclined to disregard the danger of this defect as seen of its
natural size, when it is a mere roughness on the glass, what do you
think of it _now_? You can remove it at once by scraping it with a
knife; and indeed, if through accident a touch here and there does fry,
it is your only plan to so remove it. All you can scrape off should be
scraped off and repainted every time the glass comes from the kiln; and
that brings us to the important question of _firing_.

CHAPTER VII

Firing--Three Kinds of Kiln--Advantages and Disadvantages--The
Gas-Kiln--Quick Firing--Danger--Sufficient Firing--Soft
Pigments--Difference in Glasses--"Stale" Work--The Scientific
Facts--How to Judge of Firing--Drawing the Kiln.

The way in which the painting is attached to the glass and made
permanent is by firing it in a kiln at great heat, and thus fusing the
two together.

Simple enough to say, bu