Carbon dioxide is colorless, odorless, and about 1.5 times heavier than air. Carbon dioxide may exist simultaneously as a solid, liquid, and gas at a temperature of -69.9°F (-56.6°C) and a pressure of 60.4 psia (4.16 bar), its triple point. The concentration of carbon dioxide gas in the earth’s atmosphere by volume is 0.033%. Carbon dioxide is used in gaseous, liquid, or solid form for food processing, carbonation of soft drinks, inerting, welding, lasers, shrink fitting of machinery parts, fire extinguishers, growth stimulant for plant life, and laboratory R & D.