Commodity money coins. Commodity money Commodity money is money whose value comes from a commodity of which it is made. Commodity money consists of objects that have value in themselves (intrinsic value) as well as value in their use as money. Examples of commodities that have been used as mediums of exchange include gold, silver, copper, salt, peppercorns, tea, large stones (such as Rai stones), decorated belts, shells, alcohol, cigarettes, cannabis, silk, candy, nails, cocoa beans, cowries and barley. These items were sometimes used in a metric of perceived value in conjunction to one another, in various commodity valuation or price system
Surface properties of transition metal oxides by the Hammett acidity function, formula_1 where B is the basic indicator molecule. The concentration of Brønsted acid sites can be determined by titrating a suspension of the oxide with an acid/base indicator present. However, this method is subject to many problems. For instance only Bronsted acid sites can be quantified with this method. Metal oxide surfaces can have both Brønsted and Lewis acid sites present at the same time which leads to a nonspecific interaction between the oxide and the indicator. Also, as outlined in the theory section, the perturbation of neighboring sites upon adsorption of indicator molecules compromises