Note 56 — XIX. Experimental Examination of Platina. By William Lewis, M.B. F.R.S.
Reading edition
The proportions were adjusted according to the carat weights, as it is by these, that the fineness of gold is usually expressed: A carat is the twenty-fourth part of the whole compound: thus gold of so many carats is a composition, of which so many twenty-fourths are fine gold, and the rest an inferior metal.