POTTERY AND PORCELAIN

parted by the predominating oxide. Iron produces red,
manganese black or gray, and white calcium creates a buff
or light tint. The entire absence of oxides results in a
white body which is difficult to vitrify on account of the
want of fluxes, hence it is not suited for a building
material, but by the use of a good weather clay for the
body and the application of a skin of fine white clay, the
212.vlE1V IN MODELLING DEPARTMENT, NE1V YORK ARCITECTuURAL
TERRA-COTTA CO-MPANY,
terra-cotta is made equally hardl and durable, as the skin
takes up enough of the flux from- the main body to render
it of an equal weather value without seriously affecting its
purity of color. That the New York Architectural Terra-
Cotta Company has succeeded in producing a material
answering- to these requirements is amply demonstratedl
in a specimen which is now before me, which is of a
beautiful creamy whiteness, fine texture, and of the neces-
sary hardness.

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