The surface area is typically determined by a BET measurement using a gas that is preferentially adsorbed on metallic surfaces, such as hydrogen. Using this type of measurement, almost all the exposed area in a particle of the catalyst has been shown to have Ni on its surface. Since Ni is the active metal of the catalyst, a large Ni surface area implies a large surface is available for reactions to occur simultaneously, which is reflected in an increased catalyst activity. Commercially available Raney nickel has an average Ni surface area of 100 m2 per gram of catalyst.