Close-up timelapse footage of the growth of a chemical garden. This is a solution of sodium silicate (also called glasswater, or liquid glass) to which a metal salt has been added. In this case, the salt is calcium chloride. The salt partially dissolves in the water and the ions react to form a thin layer of insoluble calcium silicate. This layer is semi-permeable, and the more concentrated salt solution inside the tube pushes outwards due to osmosis. This bursts the tube, releasing more salt solution and forming a new tube, and the process continues. As the pressure is greater further down the water column, the tubes grow upwards. The colour of the tubes depends on the metal used. This clip is speeded up 23 times.