Silver the periodic table) is useful in nuclear reactors because of its high thermal neutron capture cross-section, good conduction of heat, mechanical stability, and resistance to corrosion in hot water. The word "silver" appears in Anglo-Saxon in various spellings, such as "seolfor" and "siolfor". A similar form is seen throughout the Germanic languages (compare Old High German "silabar" and "silbir"). The chemical symbol Ag is from the Latin word for "silver", "argentum" (compare Ancient Greek ἄργυρος, "árgyros"), from the Proto-Indo-European root *"h₂erǵ-" (formerly reconstructed as "*arǵ-"), meaning "white" or "shining": this was the usual Proto-Indo-European word for the metal, whose reflexes
CB military symbol by the United States – signifying crude mustard. In the Second World War the purity of mustard gas was improved through distillation, and this purified chemical warfare agent was designated HD. When it was mixed with a thickener (Agent VV), it was given the symbol HV. Today mustard gas is indicated by the single capital letter H, but HD is still in common use. Military symbols can also reflect the name of where a chemical agent is manufactured. For example, chloropicrin has the symbol PS, which was derived from the British town in which it was manufactured during the First