Porcelain and Earthenware. 253 
twelve hundred dozen, or more pieces. ‘The bottom of each sag- 
gar is carefully covered with sand, and then sprinkled over with the 
powder of decomposed felspar, before receiving the pieces which 
are separated from each other by small triangular pieces of biscuit to 
prevent their adhering to the saggar or to each other, while in the 
kiln.* 
The heat is kept low at first, but gradually augmented until the 
kiln and its contents, attain the proper maximum. The operation of 
burning usually lasts two days and two nights, but the process varies 
in the different charges, and the workmen ascertain the state of the 
kiln, by examining “trial pieces,” which are placed so as to reveal 
the exact state, of the whole interior of the furnace. Small pieces of 
porcelain are often enclosed in one case or saggar, but large, or very 
choice pieces are separately enclosed : in no instance must one piece 
be in contact with another, and the greatest care is necessary to 
place them so that every part shall be subjected equally to the heat. 
After the saggars are placed in the furnace, the door by which they 
were carried in is walled up, and the heat raised gradually for thirty 
hours, when fuel is incessantly applied at small openings on the 
hearth by two men who relieve each other at intervals. ‘The wood 
employed is well seasoned and cut in slender pieces about a foot 
long, that the combustion may be effected with the greatest rapidity. 
When the firing is discontinued, and the smoke ceases, the chimney 
and all the apertures are closed; and the kiln with its contents are 
left to cool as gradually as possible, for thirty hours. This delay in 
withdrawing the pieces is deemed important, lest the sudden al- 
ternation of temperature should cause them to crack. The ware 
is now in the state called biscuit, and is ready for printing paint- 
ing and other ornaments, previous to receiving the covering of enam- 
elor glaze. If these were added before the conversion of the ware 
into biscuit, the shape and texture of the pieces would be injured 
by the water in the glaze; the colors would spread; printed pat- 
terns could not be transferred, or other ornaments applied, as the 
tenderness of the pieces would cause them to warp and crumble, 
and the truth of the original forms to be destroyed. 
Division of labor facilitates this part of the manufacture with the 
same profit as has been experienced in other departments of the 
arts. ‘The copper plate printer sits at one end of a room, which 
se 
* Biscuit is ware baked without glazing. 
