Using the timer Catch the time that has passed since the first trial was first with natural silica (coal) put into the fridge in a normal freezer floor.
Use the stopwatch Time elapsed since the moment of the first experimentation with substances of natural moisture. (Coal) into the refrigerator in a regular freezer.
Use a timer. Timer elapsed since the second brought the first experiment with silica gel from nature. (coal) is put into the refrigerator freezer in normal.