Bottled gas is a term used for substances which are gaseous at standard temperature and pressure (STP) and have been compressed and stored in carbon steel, stainless steel, aluminum, or composite bottles known as gas cylinders.
Carbon dioxide (chemical formula CO2) is a colorless and odorless gas that is vital to life on Earth. This naturally occurring chemical compound is made up of a carbon atom covalently double bonded to two oxygen atoms. Carbon dioxide exists in Earth’s atmosphere as a trace gas at a concentration of about 0.04 percent (400 ppm) by volume.  Natural sources include volcanoes, hot springs and geysers, and it is freed from carbonate rocks by dissolution in water and acids. Because carbon dioxide is soluble in water, it occurs naturally in groundwater, rivers and lakes, in ice caps and glaciers and also in seawater. It is present in deposits of petroleum and natural gas.