ON METALS, 269

net only very fusible, but very readily calcined by heat,
changing into a powder, or a scaly matter, which may —
be made to take all colours by the fire, from yellow to
deep red. You have scen red lead ? .

G. Yes.

Z. That is calcined lead, exposed for a considerable
time to a strong flame. Lead may even be changed
into glass, by a moderate heat; and there is a good
deal of it in eur finest glass.

G. \ ois white lead, or ceruse P

7’. It is 1ead corroded by the steam of vinegar. Lead,
im various forms, is much used by painters. Its calces
dissolve in oil, and are employed for the purpose of
thickening paint and making it dry. All lead-paiuts, ~
however, are unwholesome as long as they continue to
smell, and the fumes of lead, when melted, are also
yernicious. This is the cause why painters and
plumbers are so subject to various diseases, particularly
violent colics and palsies. The white-lead manufacture
is so hurtful to the health, that the workmen, in a very
short time, are apt to lose the use of their limbs, and
be otherwise severely indisposed.

G. I wonder, then, that anybody will work in it.

T. Ignorance and high wages are sufficient to induce
them. But it isto be lamented that in a great many
manufactures the health and lives of individuals are
sacrificed to the convenience and profit of the commu-
nity. Lead, too, when dissolved, as it may be in all
sour liquors, is a slow poison, and the more dangerous,
as it imparts no disagreeable taste. A salt of lead,
made with vinegar, is so sweet as to be called the
sugar of lead. It has been too common to put this,
or some other preparation of lead, into sour wines, in
order to cure them; and much mischief has been done
by this practice.

G. If lead be poisonous, is it not wrong to make
water-pipes and cisterns of it? |

T. This has been objected to; but it does not ap-
pear that water can, of itself, dissolve any of the lead.