At standard temperature and pressure, the density of carbon dioxide is around 1.98 kg/m, about 1.67 times that of air.Carbon dioxide has no liquid state at pressures below 5.1 standard atmospheres (520 k Pa).
His interpretation was that the rest of the charcoal had been transmuted into an invisible substance he termed a "gas" or "wild spirit" (spiritus sylvestre).
The properties of carbon dioxide were studied more thoroughly in the 1750s by the Scottish physician Joseph Black.
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.
The combustion of all carbon-based fuels, such as methane (natural gas), petroleum distillates (gasoline, diesel, kerosene, propane), coal, wood and generic organic matter produces carbon dioxide and, except in the case of pure carbon, water.
As an example, the chemical reaction between methane and oxygen: from most metal carbonates.
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.
Being diprotic, carbonic acid has two acid dissociation constants, the first one for the dissociation into the bicarbonate (also called hydrogen carbonate) ion (HCO is a weak electrophile.
Its reaction with basic water illustrates this property, in which case hydroxide is the nucleophile. For example, carbanions as provided by Grignard reagents and organolithium compounds react with CO Carbon dioxide is colorless. At higher concentrations it has a sharp, acidic odor.
It is returned to water via the gills of fish and to the air via the lungs of air-breathing land animals, including humans.