Calcium carbonate is also used in the purification of iron from iron ore in a blast furnace. The carbonate is calcined in situ to give calcium oxide, which forms a slag with various impurities present, and separates from the purified iron.
One re-hydrated package fills about 15-20 dishes. Mix 1 level teaspoon of dehydrated agar with 100 ml (3/8 cup) of water and then bring to a boil to make 100 ml of agar solution. Prepare Petri Dishes: Fill petri dishes to just cover the bottom. Typical 90-100mm dishes require 10-15 ml agar. Rotate the dish to obtain even surface coverage. Cover the dish immediately and let stand until firm. Store upside down in the refrigerator until ready to use.
1 Substitute agar powder for gelatin using equal amounts. 2  1 tablespoon of agar-agar flakes is equal to 1 teaspoon of agar powder. 3  To set 1 cup of liquid, use 1 teaspoon of agar powder or 1 tablespoon of agar-agar flakes.