ff enough flesh or fat, or to the specimen being
mounted in a case before it was sufficiently dry. If it be mildew, the
specimen must come out of the case and be properly dried. If it be
merely crystallisation of impure alum, the crystals must be washed off
with warm water from time to time as they form, until no more appear.
It must be remembered, however, that a damp house, or juxtaposition to
a wet wall, will ruin the most carefully mounted specimens.

Correspondents may be quite sure that neither the method nor the
formula are to blame in the matter. The great point is to wipe off the
mildew or crystals as fast as they appear until no more form, which
will determine when the specimen is thoroughly dry.

How to solder, either by the blowpipe or by the "bit," is now and then
useful knowledge. Any mechanic will impart this for a consideration.

CHAPTER XIII.

CASES, MOUNTS, SHIELDS, EGG CABINETS, ROCKWORK, FERNS, GRASSES,
SEA-WEEDS, ETC, FOR "FITTING UP."

CASES can be made in all styles. The oldest is the "box," which needs
no description. Next in age is the "canted-corner case," a most odious
abomination beloved of the amateur; the shape of the ground plan being
as Fig. 38. A to A the front, B to B the back, C C C is glass, the
points A A are wooden or metal uprights, pinning together top and
bottom; B B B B is wood; hence it follows that all the space outside
the dotted lines is useless, or if used at all, the uprights (A A)
cross perhaps the most important part of the work, so that this shaped
case resolves itself into the following difficulty: either the case is
too large for the object, or two lines cross it.

Fig. 38--Plan of "canted-corner" case.

The usual glass-ended square case is easily made by any amateur joiner
in this wise: Take two pieces of wood for top and bottom to size
required, plane and square them up together to ensure their being
exactly alike; then, with a "plough" plane, set to 0.375 in, "plough
out" all around the front and sides of each to half its thickness.
Take the back and nail it to the top and bottom with brads; having
done which, next take two pieces of wood for the uprights of
sufficient thickness to suit the case--too great thickness being
guarded against.

Fig. 39--Section of "uprights" or pillars of square case.

Let us, however, assume that each of these pieces is 0.75 in. square,
the height immaterial, "plough" these out on two sides, the "plough"
still set at 0.375 i