Page:Book of record of the time capsule of cupaloy (New York World's fair, 1939).djvu/15

 physical appearance, as indicated by our skeletons. But certainly many of the perishable things of our culture will have been lost in the course of time, unless special efforts are made to preserve them.

In these matters we have taken counsel of archaeologists, historians, metallurgists, engineers, chemists, geophysicists, and other technical men of our time. We have given much study not only to the selection of the items to be preserved, but also to methods of preserving them for so long a time & of leaving this message about them.

Our first concern was the construction of the Time Capsule itself, a problem of great complexity. Our experience with artificial materials is too short to give us certain knowledge of their ability to withstand the corrosive effects of thousands of years, yet the older mineral materials, including stone and glass, are too brittle and too difficult to work, are liable to breakage from pressure or earthquake, and are too difficult to detect when buried in the earth.

We have decided that the best possible material is a metallic alloy of high corrosion resistance & considerable hardness, of nonferrous nature, and preferably containing a high percentage of copper. Of all the tools used by ancient peoples, those of stone and copper have come down to us from farthest in the past.

It happens that a copper alloy fulfilling these specifications has recently been developed. Known as Cupaloy, it is 99.4 per cent copper, .5 per cent chromium, and .1 per cent silver. This material may be tempered to a hardness similar to that of mild steel, yet has a resistance to corrosion equal to pure copper. In electrolytic reactions