At the bottom of, for example, the South China Sea, is a substance known as methane clathrate. It's a crystal of water ice with gaps in which methane molecules are enclosed. These gaps are present in common ice as well, but they aren't filled by any substance. The chemical formula of this clathrate is CH₄·5.75 H₂O. How many m³ of methane can be released to the atmosphere at temperature 0°C and pressure 100 kPa from 1 m³ of the clathrate? Water ice density is 917 kg·m⁻³. Sweet memories of Katka's high school years.