Provisional and Definitive Tests

  I've been trying to come up with a good example from the History of Science to illustrate the comparison of test procedures and one is the assessment of the purity of metals. One test might be the use of Archimedes' principle to test the specific gravity of a given sample. On the other hand one might take cupellation as the definitive test for purity but he disadvantage of cupellation is that it is destructive so one might prefer a provisional test like the use of Archimedes' principle.

Cupellation is used in the Trial of the Pyx for the assay of coinage. This method dates from ancient times. Modern silver standards are well regulated. For example sterling silver is required to have a fineness of 925.

A modern example of the purification of metals similar to cupellation is the Czochralski process. X-rays can also be used for assaying metals.