The Artist's Assistant, In the Study and Practice of Mechanical Sciences: Calculated for the Improvement of Genius. Illustrated with Copper-Plates — Birmingham, [ca. 1785]

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i58 THE ARTIST'S ASSISTANT.

maining on the furface, or at leaft entering; vcrv lit-
tie. When the painting of all the pieces is finifhed,
they are carried to the furnace, or oven, to anneal,
or bake the colours.

The furnace here ufed is fmall, built of brick,
from eighteen to thirty, inches fquare; at fix inches
from the bottom is an aperture to put in the fuel, and
maintain the fire. Over this aperture is a grate,
made of three-fquare bars of iron, which travefe
the furnace, and divide it into two parts. Two
inches above this partition, is another little aper-
ture, through which they take out pieces to exa-
mine how the coction goes forward. On the grate
is placed a fquare earthen pan, fix or feven inches
deep; and five or fix inches lefs every way than the
perimeter or the furnace. On the one fide hereof is
a little aperture, through which to make trials,
placed directly oppofite to that of the furnaces def-
tined for the fame end. In this pan are the pieces
of glafs to be placed in the following manner; Firlt,
the bottom of the pan is covered with three ft rata,
or layers of quick lime pulverized; thole llrata
being feparated by two others of old broken glafs,
the defign whereof is to fecure the painted glafs
from the too intenfe heat of the fire. This done,
the glaffes are laid horizontally on the laft or upper-
moil layer of lime.

The firft row of glafs they cover over with a
layer of the fame powder, an inch deep; and over
this they lay another range of glaffes, and thus al-
ternately till the pan is quite fall; taking care that
the whole heap always end with a layer of the lime
powder.

The
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