Chemical substance made in a laboratory. Other chemical substances commonly encountered in pure form are diamond (carbon), gold, table salt (sodium chloride) and refined sugar (sucrose). However, in practice, no substance is entirely pure, and chemical purity is specified according to the intended use of the chemical. Chemical substances exist as solids, liquids, gases, or plasma, and may change between these phases of matter with changes in temperature or pressure. Chemical substances may be combined or converted to others by means of chemical reactions. Forms of energy, such as light and heat, are not matter, and are thus not "substances" in this
Common toad the rate for deaths among males likely to be of a similar order. The main toxic substance found in the parotoid gland and skin of the common toad is called bufotoxin. It was first isolated by Heinrich Wieland and his colleagues in 1922 and they succeeded in identifying its structure about 20 years later. Meanwhile, other workers succeeded in isolating the same compound and its parent steroid bufotalin from the Japanese toad ("Bufo japonicus"). By 1986, researchers at the Arizona State University had succeeded in synthesizing the toad venom constituents bufotalin, bufalitoxin and bufotoxin. The chemical formula of bufotoxin is