zinc together with copper, tin, antimony and lead. Another form is made
with nearly 90 per cent of tin combined with copper and antimony.

Gun metal bronze is made from 90 per cent copper with 10 per cent of tin
and is used for heavy bearings, brackets and highly finished parts.

Phosphor bronze is used for very strong castings and bearings. It is
similar to gun metal bronze, except that about 1-1/2 per cent of phosphorus
has been added.

Manganese bronze contains about 1 per cent of manganese and is used for
parts requiring great strength while being free from corrosion.

German silver is made from 60 per cent of copper with 20 per cent each of
zinc and nickel. Its high electrical resistance makes it valuable for
regulating devices and rheostats.

_Tin_ is the principal part of _babbitt_ and _solder_. A
commonly used babbitt is composed of 89 per cent tin, 8 per cent antimony
and 3 per cent of copper. A grade suitable for repairing is made from
80 per cent of lead and 20 per cent antimony. This last formula should not
be used for particular work or heavy loads, being more suitable for
spacers. Innumerable proportions of metals are marketed under the name of
babbitt.

Solder is made from 50 per cent tin and 50 per cent lead, this grade being
called "half-and-half." Hard solder is made from two-thirds tin and
one-third lead.

Aluminum forms many different alloys, giving increased strength to whatever