2H or D. Exists in the diatomic state, D2; mol wt 4.028. Stable, non-radioactive isotope of hydrogen, q.v. Shows ortho and para isomerism. Prepd by electrolysis of heavy water, D2O (obtained by the H2S/H2O exchange process) or by fractional distillation of liq hydrogen: Urey et al., Phys. Rev. 39, 164 (1932); Spevack, US 2787526 (1957 to USAEC). The hydrogen bomb contains lithium deuteride (LiD) as explosive and plutonium (Pu) as initiator. After detonation by Pu the following reaction sequence takes place (nuclear fusion): 6Li + D = 24He; 6Li + n = 4He + T; 6Li + T = 24He + n (n = neutrons, coming from Pu in the second reaction). Since the explosion does not start by itself, there is no critical mass and no limit to the size of the bomb. Use as chemical tracer: Wiberg, Chem. Rev. 55, 713-743 (1955). Toxicology: J. F. Thomson, Biological Effects of Deuterium (Pergamon Press, 1964). Review: Mackay, Dove in Comprehensive Inorganic Chemistry vol. 1, J. C. Bailar, Jr. et al., Eds. (Pergamon Press, Oxford, 1973) pp 77-116; Chemistry of the Elements, N. N. Greenwood, A. Earnshaw, Eds. (Pergamon Press, New York, 1984) pp 38-74; J. J. Katz in Kirk-Othmer Encyclopedia of Chemical Technology vol. 8 (Wiley-Interscience, New York, 4th ed., 1993) pp 1-17.