268 
RERAMIC STUDIO 
thickness of the wall of the firing chamber, thus increasing the 
general resistance to pressure and preventing as much as 
possible the loss of heat through the door which is so well 
known to firers. This I do and the spacfe between the two 
walls is filled with dry fine sand. The object is to increase the 
thickness of the door and to hermetically close it so as to 
prevent infiltration of air during the firing. This sand is made 
of fragments of lute which are gathered after firing and ground. 
While constructing the door, when two-thirds are built, 
the movable spyhole is placed across the two walls, in the axis 
of the center of the cone sagger (Fig. 77) . This spj^'hole is in 
the shape of a square box. It is in fire brick and open at both 
ends. The outside opening is closed with a stopper of same 
material which fits it well. This stopper is pierced with a hole 
closed with a piece of white glass through which the different 
phases of firing may be watched (Figs. 36, 37, 38, p. 195, 
Jan. 1904). 
The laaking chamber is closed onlj^ by one wall stronglj? 
washed with mortar. It has no spyhole. 
f'l7a 
When the door is completed, the two movable parts of the 
iron bracuig which goes over the door, are closed (Fig. 78). 
These two parts are on hinges and are tightlj^ stretched by 
means of a strong bolt. 
As a conclusion to this article, I will advise the beginner 
to make his placing material, or have it made, with the mater- 
ials I have mentioned, until he has found their equivalent or 
better materials in his own country. The learned article of 
Mr. Charles F. Binns satisfies me that it will be easy to find 
these. To avoid severe disappointments, the beginner will 
do well to follow my instructions closely. He will first 
bake his placing material, will learn the placing of simple 
forms, fire without giving too much attention to the exact 
filling of saggers, lie will stop his bungs about 4 inches from 
the vault of the firing chamber and will prop them solidly. 
He will fix up some machine to make lute and will give the ut- 
most care to his first setting. With a little practice every 
precaution to be taken will come to the mind naturally. At 
each setting he will take into account the different degrees of 
sensitiveness of the glazes, so that some will be placed in the 
hottest parts, others in the j:)arts of less intense heat in the kiln. 
As the Ijase of the bung is less hot and more oxidising as a rule 
he will place there the colors which need for a good develop- 
ment a very oxidising atmosphere, like those based upon 
Cobalt, manganese or chrome, or the colored glazes, the fusi- 
bility of which causes them to easih^ flow, which is a great 
defect of these glazes. 
GUP AND SAUCER— RUSSELL GOODWIN 
To be executed in two shades of gold or gold and yellow brown lustre. 
