Amount of substance in use in chemical engineering in the United States is the pound-mole, having the symbol lb-mol. One pound-mole is . When quoting an amount of substance, it is necessary to specify the entity involved, unless there is no risk of ambiguity. One mole of chlorine could refer either to chlorine atoms, as in 58.44 g of sodium chloride, or to chlorine molecules, as in 22.711 liters of chlorine gas at STP. The simplest way to avoid ambiguity is to replace the term "substance" by the name of the entity or to quote the empirical formula. For example: Amount of substance
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