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Test of Platinum-Iridium
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Test of Platinum-Iridium

 1889  NIST Museum Collection
This sample of platinum-iridium was used by the Office of Weights and Measures for testing its properties with regard to the ruling of scales. Platinum-iridium was being used at this time for the manufacture of the International Meter and Kilogram and for the construction of the national prototypes, two of which would arrive in the United States the following year. Platinum-iridium is much less likely to corrode than brass. The material is also harder and more rigid than brass. Its greater rigidity (modulus of elasticity) makes it more suitable than brass for length standards.