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 Do not touch the agar or you will contaminate it with bacteria on your fingers. 2  Now it s time to collect and grow your bacteria (or fungi) on the agar Petri dishes. 3  Note: the Petri dishes can be stored in the fridge for 1-2 days before use. Add beef stock powder, sugar and gelatin to the boiling water and stir for a minute until all the ingredients have dissolved. 2  Cool your new agar mixture slightly for 10 minutes. 3  The mixture needs to be still hot to avoid the gelatin setting in the saucepan and to prevent contamination from bacteria in the air.