SOME NOTES ON PORCELAIN
Part Two
By John Reeve

Thie te part tuo of John Reeve's paper on porcelain
bodtes. The ftret part, which we printed tn the last
tesue of The Weatern Potter, haa prompted many
favourable eanmenta from potters throughout the
country. Once again, The Weetern Potter axrpreasses
thanks to Mr. Reevoa for tne permisaton ao publish
thie article, Part taree wili be printed tn ou

Mert tease.

SILICA, TIME AND PARTICLE SIZE

The Chinese materials for porcelain-making, PETUNSE
and KAQ-LING, correspond to CORNISH STONE and CHINA
CLAY. That is what we generally say, and it is
certainly a ceneralization, for there is no combina-
tion of our Cornish stone (or feldspar or nepheline
syenite) which will combine with our china clay to
produce a porcelain body at cone 8-10. The permutations
are invariably too low in SILICA and we must always
augment the silica content with quartz or flint. The
difference between the silica in clay and the silica
(s quartz or flint is not a difference in chemistry
($i0, is Si0,) but a physical difference in size. Clay
contains arin Wiitiee silica which dissolves readily;
quartz and flint are only as fine as they are milled
and only dissolve with difficulty.

16