vessels, plates, parts of
machines, etc, can often be made in the laboratory in less time than
it would take to explain to the potter what is required. For this
purpose any good pipeclay may be employed. I have used a white
pipe-clay dug up in the laboratory garden with complete success.

The clay should be kneaded with water and squeezed through a cloth to
separate grit. It is then mixed with its own volume or thereabouts of
powdered porcelain evaporating basins, broken basins being kept for
this purpose. The smoothness of the resulting earthenware will depend
on the fineness to which the porcelain fragments have been reduced. I
have found that fragments passing a sieve of sixty threads to the inch
run, do very well, though the resulting earthenware is decidedly
rough.

The porcelain and clay being thoroughly incorporated by kneading, the
articles are moulded, it being borne in mind that they will contract
somewhat on firing. [Footnote: The contraction depends on the
temperature attained as well as on the time. An allowance of one part
in twelve will be suitable in the case considered.] The clay should
be as stiff as is convenient to work, and after moulding must be
allowed to get thoroughly dry by standing in an airy place; the
drying must not be forced, especially at first, or the clay will
crack.

Small articles are readily fired in a Fletcher's crucible furnace
supplied with a gas blow-pipe; the furnace is heated gradually to
begin with. When a dull red heat is attained, the full power of the
blast may be turned on, and the furnace kept at its maximum
temperature for three or four hours at least, though on an emergency
shorter periods may be made to do.

The articles are supported on a bed of white sand; after firing, the
crucible furnace must be allowed to cool slowly. It must be
remembered that the furnace walls will get hot externally after the
first few hours, consequently the furnace must be supported on bricks,
to protect the bench.

The pottery when cold may be dressed on a grindstone if necessary.
This amateur pottery will be found of service in making small fittings
for switch-boards, commutators, and in electrical work generally.

Pottery made as described is very hard and strong, the hardness and
strength depending in a great degree on the proportion of powdered
porcelain added to the clay, as well, of course, as on the quality of
both of these materials.

It is a good plan to kne