206 MASSICOT. RED LEAD. LITHARGE, &C. 
as a solvent, and combining with, and precipitating 
them. We are informed that white lead, dangerous as 
it is, was in great request among the Roman ladies as 
a cosmetic. It is sometimes used as an external appli- 
cation for ulcers and other kinds of sores. 
Massicot is a mineral substance of yellow colour, 
used for painting, and prepared from the dross or 
pellicle that is formed by the melting of lead. 
Red Lead, or Minium, is a mineral substance of red 
colour, used for painting, and made, by a tedious and 
troublesome process, from massicot. For this purpose 
the massicot is ground to a fine powder, put into a 
furnace^ and constantly stirred, whilst the flame of the 
burning coals plays against its surface for about forty- 
eight hours, when it is converted into a red powder, 
which is the article under consideration. It is subse- 
quently passed through very fine iron sieves. The use 
of red lead as a pigment is well known ; but as it is 
liable to turn black, vermilion is generally preferred to 
it. It is sometimes employed in medicine as an exter- 
nal application for abating inflammations, for cleansing 
and healing- ulcers, and the like ; and is used in the 
manufacture of glass. 
Litharge is another kind of oxide of lead. This is 
prepared by exposing calcined lead to a brisk fire for a 
certain length of time. The substance, on cooling, 
concretes into a flaky matter. Litharge is used by 
potters for the glazing of earthen-ware, but vessels that 
are glazed with it are thereby rendered unwholesome. 
It is also employed, in the composition of the finer 
kinds of glass, for the purpose, not only of giving 
them greater transparency, but also of rendering them 
capable of sustaining sudden changes from heat to 
cold, and of giving to them a susceptibility of being 
cut without breaking. It, however, adds considerably 
to the weight of the glass. 
Litharge Plaster, or Diachylon Plaster, as it is more 
-equently called, is prepared by boiling two pints of 
alive oil with one pint of litharge, adding water, and 
