Copper(II) chlorate heated, giving off a yellow gas, which contains chlorine, oxygen and chlorine dioxide. A green solid is left that is a basic copper salt. Sulfur is highly reactive with copper chlorate, and it is important not to cross contaminate these chemicals, for example in pyrotechnic making. François-Marie Chertier used tetrammine copper chlorate to colour flames blue in 1843. This material was abbreviated TACC with formula Cu(NH)(ClO). TACC explodes on impact. The substance became known as Chertier'c copper for use in blue coloured pyrotechnics. However its deliquescence causes a problem. Mixtures with other metal salts can yield violet or lilac colours
Barium is then reduced by carbon to barium sulfide: The water-soluble barium sulfide is the starting point for other compounds: reacting BaS with oxygen produces the sulfate, with nitric acid the nitrate, with carbon dioxide the carbonate, and so on. The nitrate can be thermally decomposed to yield the oxide. Barium metal is produced by reduction with aluminium at . The intermetallic compound BaAl is produced first: BaAl is an intermediate reacted with barium oxide to produce the metal. Note that not all barium is reduced. The remaining barium oxide reacts with the formed aluminium oxide: and the overall reaction is