immutabilty

Updated: May 8, 2025

Iridium is mixed with platinum in order to increase its strength and durability. The normal standards of the metrical system are made of platinum-iridium on account of its known immutabilty. In 1882, platinum stood 15 per cent. below its present value; but its increased employment for industrial purposes led to the subsequent improvement in price.

Various - Scientific American Supplement, No. 520, December 19, 1885