Note 49 — PART I. THE CHANGES UNDERGONE BY ANTIQUITIES IN EARTH AND IN AIR.

It should be observed that the change in the proportions according to Schuler (see page 24) is only true of the analysis, Column III. In Columns I and II the amount of metallic copper of the patina is indeed smaller, but so is also that of lead and especially of tin. But this may be due to a faulty method in the determination of tin noticed by Olshausen (v. “Verhandl. d. Berl. anthropol. Ges.,” 1897, p. 349). The different proportion of the copper compounds in the patina should also be noted, Schuler giving carbonate and hydrate in the proportion 1:1, Arche and Hassack once as 1:2, and again as the result of two analyses as 1:3.