A simple lead glaze is generally used for clay tobacco pipes. The following may be taken as examples, (a) Lead oxide (litharge), 45 parts: sand, 35 parts; common salt, 6 parts, {b) White lead, 53 parts; Cornish stone or felspar, 16 parts; white flint glass, 5 parts. The glaze may be melted in a crucible, and the stems of the pipes (which should have been previously burnt) dipped in. For green colour, use 5 per cent, of oxide of copper; for red, .3 per cent, of red oxide of iron.