You want to enter the castle. There is a large, thick, oak door with a large key slot. Attached next to the door is a barometer (pressure = 760 mm Hg), and a thermometer showing the temperature to be 28deg.C. On a nearby table is a Bunsen burner, a large bottle of pure water, a large beaker, a very accurate graduated cylinder and a large iron key whose mass has been carefully measured as 147 grams. A letter is posted on the door:

Exactly what will you do to get into the door?