Stalactite a cave it will drip down. When the solution comes into contact with air the chemical reaction that created it is reversed and particles of calcium carbonate are deposited. The reversed reaction is: An average growth rate is a year. The quickest growing stalactites are those formed by a constant supply of slow dripping water rich in calcium carbonate (CaCO) and carbon dioxide (CO), which can grow at per year. The drip rate must be slow enough to allow the CO to degas from the solution into the cave atmosphere, resulting in deposition of CaCO on the stalactite. Too fast
Calcium carbonate into air. However, in a charcoal fired kiln, the concentration of CO will be much higher than it is in air. Indeed, if all the oxygen in the kiln is consumed in the fire, then the partial pressure of CO in the kiln can be as high as 20 kPa. The table shows that this partial pressure is not achieved until the temperature is nearly 800 °C. For the outgassing of CO from calcium carbonate to happen at an economically useful rate, the equilibrium pressure must significantly exceed the ambient pressure of CO. And for it to happen rapidly, the