2087. Because they come in contact with the fire, and (while they are covered with black soot) absorb heat freely from the burning coals.
2088. Why are dinner-covers made of bright tin or silver?
2089. Because light-colored and highly-polished metal is a very bad radiator of heat; and, therefore, bright tin or silver will not allow the heat of the cooked food to escape through the cover by radiation.
2090. Why should a meat-cover be very brightly polished?
2091. If the cover be dull or scratched, it will absorb heat from the food; and instead of keeping it hot, it will make it cold.
2092. Why should a silver meat-cover be plain, and not chased?
2093. Because, if the cover be chased, it will absorb heat from the food; and instead of making it hot, will make it cold.