3. Peroxide of manganese, 3 parts; zaffre, 1 part; mix, and add it, as
required, to white flux.
=Enamel, Blue.= _Prep._ 1. White 'frit' or 'flux,' coloured with oxide of
cobalt.
2. Sand, red lead, and nitre, of each 10 parts; flint glass or ground
flints, 20 parts; oxide of cobalt, 1 part, more or less; depending on the
desired depth of colour.
=Enamel, Brown.= _Prep._ 1. Manganese, 5 parts; red lead, 16 parts; flint
powder, 8 parts; as before.