Hence: That which affords effectual protection or
security; a sateguard; as, the trial by jury is the palladium of our
civil rights.

A rare metallic element of the light platinum group,
found native, and also alloyed with platinum and gold. It is a
silver-white metal resembling platinum, and like it permanent and
untarnished in the air, but is more easily fusible. It is unique in its
power of occluding hydrogen, which it does to the extent of nearly a
thousand volumes, forming the alloy Pd2H. It is used for graduated
circles and verniers, for plating certain silver goods, and somewhat in
dentistry. It was so named in 1804 by Wollaston from the asteroid
Pallas, which was discovered in 1802. Symbol Pd. Atomic weight, 106.2.