hould. be mixed to cover the bottom of the
dish about 1/2 in. thick. Pour the plaster into the dish over the
print and allow to stand until it becomes quite hard. The cast can
then be removed and the print should be fast to it. If the print
or plaster is inclined to stick, take a knife and gently pry
around the edges and it can be removed without breaking.

Prints of any size may be used by having the mold or dish large
enough to leave a good margin. This is a very important point as
it is the margin that adds richness to all prints. Platinum or
blueprint papers work well, but any kind that will not stick may
be used. After the plaster has thoroughly dried, any tint may be
worked on the margin by the use of water colors; if blueprints are
used, it is best to leave a plain white margin.

** Iron Rest for an Ironing Board [288]

A flatiron rest can be made on an ironing-board by driving a
number of large tacks into one end of the board. The tacks should
be about 1 in. apart and driven in only part way, leaving about
1/4 in. remaining above the surface of the board. The hot iron
will not burn the wood and it cannot slip off the tacks. This iron
rest is always with the board and ready when wanted. --Contributed
by Beatrice Oliver, New York, N. Y.

[Illustration: Iron Rest]

** Instantaneous Crystallization [288]

Dissolve 150 parts of hyposulphite of soda in 15 parts of water
and pour the solution slowly into a test tube which has been
warmed in boiling water, filling the same about onehalf full.
Dissolve in another glass 100 parts of acetate of soda in 15 parts
of boiling water. Pour this solution slowly on top of the first in
such a way that it forms an upper layer, without mixing the
solutions. The two solutions are then covered over with a thin
layer of boiling water and allowed to cool.

[Illustration: Crystallization]

Lower into the test tube a wire, at the extremity of which is
fixed a small crystal of hyposulphite of soda. The crystal
traverses the solution of acetate without causing trouble, but
crystallization will immediately set in as soon as it touches the
lower hyposulphite of soda solution, as shown at the left in the
sketch.

When the hyposulphite of soda solution becomes crystallized, lower
in the upper solution a crystal of acetate of soda suspended by
another wire, as shown in the right of the sketch, and this will
crystallize the same as the other solution.

** Decoloration of