Water is then added and
the compound turned into the grinding-mill where it is ground for an
entire day. Sometimes, however, a different process is preferred and
the material is put into a kiln and melted instead. In either case it
must finally be worked into a smooth liquid which can be strained
through fine lawn. It is then sent to the agitators and constantly
stirred until it can be pumped into the storage tanks in the
dipping-room."
"That is just what I wanted to know," said Theo.
"Any more questions?"
The boy shook his head.
"Not now, thank you."
"Then as we have finished here shall we go up to the clay-shop?"
"Yes, I am ready," Theo affirmed. Then as if confronted by an
afterthought he asked:
"Is the porcelain made here bone china or ----"
"Spar?" put in Mr. Marwood as the lad hesitated.
"I don't think I understand."
"Feldspar."
"Oh, then I know," cried Theo. "I did not realize you classified
porcelains as bone or spar."
"We do," was the quick reply. "Our finest grade of porcelain has
little or no phosphate of calcium, or ground bone, in it. But it is in
consequence very costly, and therefore to meet the demands of the
market we also manufacture a porcelain slightly strengthened with a
bone element.
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