Barium hydroxide, it absorbs very little CO in aqueous solutions and is therefore insensitive to atmospheric fluctuations. This property is used in calibrating pH equipment. Volatile barium compounds burn with a green to pale green flame, which is an efficient test to detect a barium compound. The color results from spectral lines at 455.4, 493.4, 553.6, and 611.1 nm. Organobarium compounds are a growing field of knowledge: recently discovered are dialkylbariums and alkylhalobariums. Barium found in the Earth's crust is a mixture of seven primordial nuclides, barium-130, 132, and 134 through 138. Barium-130 undergoes very slow radioactive decay to xenon-130 by
Barium oxide at 1175K. The reaction was used as a large scale method to produce oxygen before the air separation became the dominant method in the beginning of the 20th century. The method was named after its inventors the Brin process. Barium oxide is made by heating barium carbonate. It may also be prepared by thermal decomposition of barium nitrate. Likewise, it is often formed through the decomposition of other barium salts. Barium oxide is an irritant. If it contacts the skin or the eyes or is inhaled it causes pain and redness. However, it is more dangerous when ingested. It can