thermometer. This design is in what is known as
two-part symmetry. A line is drawn down the paper and one-half of
the outline and decoration worked out. This done, the paper is
folded along the center line, a piece of carbon paper is inserted
between the folds and the design transferred on the inner surfaces
by tracing with a pencil over the half of the outline previously
drawn. Trace the design and outline upon the metal, using the
carbon paper.

Cut out the outline with metal shears and file the edges smooth.

With a small brush and ordinary asphaltum or black varnish, paint
the design, the margin and the entire back of the metal. When this
coat has dried put on a second and then a third. The asphaltum is
to keep the acid into which the metal is to be immersed later from
eating any part of the metal but the background. Two coats or more
are needed to withstand the action of the acid.

The acid bath is composed of nitric acid and water, about half and
half, or, possibly, a little less acid than water, the mixture
being made by pouring the acid into the water, not the water into
the acid, which is dangerous. Keep this solution off the hands and
clothes, and do not inhale the fumes.

Put the asphalt-coated metal in the bath and allow it to remain
for four or five hours, depending upon the thickness of the metal
and the strength of the acid. With a stick, or a pair of old
tongs, take the metal out of the acid occasionally and examine it
to see how deep the acid has eaten it--1/32 in. is about right for
the No. 16 gauge.

When etched to the desired depth, remove the piece and with an old
knife' scrape off the asphaltum. Finish the cleaning by scrubbing
with turpentine and a brush having stiff bristles.

If the metal is first covered with turpentine and then heated over
a flame, all the colors of the rainbow will appear on its surface.
These colors fade away in the course of a long time, but they can
be easily revived. Another way to get these colors is to heat the
metal and then plunge it into the acid bath quickly.

A green finish is obtained by painting the background with an acid
stain composed as follows: 1 part ammonia muriate; 3 parts ammonia
carbonate; 24 parts water. If one coat does not give the depth of
color desired, repeat as many times as is necessary, allowing each
coat time to dry before applying the next.

To "fix" this color so that it will not rub off, and to keep the
metal from tarnishing, ap