The three illustrations on page 298 are designed to represent traps set
in lead pipe and show vividly the difference between this material and
iron piping.
[Illustration: Fig. 159.]
Lead is one of the elementary substances of which the world is formed;
it ranks with gold, silver, tin, etc., in being an unmixed metal.
It melts at about 617° Fahrenheit, and is, bulk for bulk, 11-4/10
heavier than water (gold being 17-5/10 heavier and wrought iron 7-7/10
heavier). The tenacity of lead is extremely low, a wire 1/18th of an
inch breaks with a weight of 28 lbs.; in comparison, its tenacity is
only one-twentieth that of iron; it is so soft that it may be scratched
with the thumb nail. If a very strong heat is applied lead boils and
evaporates; it transmits heat very slowly; of seven common metals it is
the worst conductor, therefore it is good for hot water pipes. Mixed
with a sufficient quantity of quicksilver it remains liquid.
An advantage to be found in the use of lead is its durability and
comparative freedom from repairs. In London, soil and drain water pipes
which have been fixed 300 to 500 years are as good now as the day they
were first made—while iron pipe cannot be expected to last over 10 or
20 years or 30 at the utmost.
Fig. 159 represents the general system of house piping and drainage
applicable also to shops, public buildings, etc. A exhibits the drain
or sewer. A-C represents the sewer connection, so called with a running
trap, B. “C” at the end of the lower pipe exhibits a soil pipe elbow,
with hand hole for cleaning out closed by a screw plug. This drain
should have a regular fall or inclination and this elbow provides for
that. C-D shows the rain water leader (conductor).
E and F is a soil pipe 3, 4, 5, or 6 inches in diameter. Note, pipes
draining water closets are called “soil pipes”; those draining other
fixtures “waste pipes.” N and O represent water-closet flanges; F and
H are roof connections; L exhibits double and single =Y= branches to
receive waste-pipes from baths, bowls, or sinks. The plumber makes this
connection, always trapping the lead waste-pipe and then soldering it
to a _brass_ nipple.