food preservation Keeping food for long periods (1) ………………………… time was historically a huge problem. This proved especially crucial (2) ………………………… times when agricultural production (3) ………………………… severely limited by weather or crop failure. People commonly used ice to (4) ………………………… food fresh but, of course, ice itself melts relatively quickly. In 1859 an American, John Mason, (5) ………………… a glass jar with a metal screw-on lid, creating a perfect seal and making (6)....…possible to preserve food that would previously not have remained edible. Mason’s jar is still (7) ………………………… use throughout the world. An even (8) ………………………… successful method for keeping food by canning it in metal containers was perfected between 1870 (9) ………………………… 1920 by Englishman Bryan Donkin. This preserved food beautifully, though the early iron cans were expensive, heavy and difficult to open. A breakthrough came in the 1880s with the development of lighter materials (10) ………………………… also enabled mass production of cans.