Are tin cans really made of tin?

The Boston Globe: "The history of the tin can dates back as far as 1795, when the French government was interested in how to preserve food for Napoleon’s troops and offered a prize for a good solution.

A Parisian named Nicholas Appert put partially cooked food in glass bottles, then placed the bottles in boiling water to heat them and drive out the air. Tightly corked or otherwise sealed, the food in these containers kept well, and Appert was awarded the prize.

In 1810, Peter Durand, an Englishman, realized that one could replace the fragile glass containers with cans made of “tinplate’’ - tin-plated iron - with the sealing done by soldering the cans shut. The iron provided strength while the tin protected the can from corrosion."