Of chalk and paper (612--617).
612.
To make points [crayons] for colouring dry. Temper with a little wax
and do not dry it; which wax you must dissolve with water: so that
when the white lead is thus tempered, the water being distilled, may
go off in vapour and the wax may remain; you will thus make good
crayons; but you must know that the colours must be ground with a
hot stone.
613.
Chalk dissolves in wine and in vinegar or in aqua fortis and can be
recombined with gum.
614.