184 
FINDING NATURE’S TREASURES 
into the clay to keep it from cracking so easily. They 
baked the dishes in the fire to make them strong. Then 
they painted them with pretty colors, something like our 
dishes.” 
“Mother has some beautiful dishes,” said Fred, “but 
most of them are white.” 
“Those dishes are made of white clay,” explained 
Uncle Jack. “They are made by machinery and baked 
in great ovens that are very, very hot. Sometimes other 
things are put with the clay to make the dishes stronger.” 
“Is anything else made of clay?” asked Fred. 
“Bricks are made of clay mixed with a little sand and 
put into a mold. Then the bricks are placed in big ovens 
and baked, also.” 
“The clay that Mother’s dishes are made of isn’t like 
the soil in our garden, though,” said Fred. 
“Dishes are made of rock flour,” continued Uncle Jack. 
The children looked at Uncle Jack in surprise. 
“What do you mean by rock flour?” asked Fred. “Rocks 
are hard, and this wet clay is soft.” 
“Grains of wheat are hard, aren’t they?” asked Uncle 
Jack. 
“Yes,” answered Fred. 
“But when the flour made by grinding that wheat is 
mixed with water, it is soft, very much like this wet 
clay,” explained Uncle Jack. “When a certain kind of 
rock called feldspar is ground up like flour, we say it is 
clay, but it is really rock flour.” 
“How do the feldspar rocks get ground up?” asked 
Bess. 
