Spelter been used since about the 1860s to make statues, tablewares, and lamps that resemble bronze. Spelter is soft and breaks easily. To test for spelter, scratch the base of the piece. Bronze will appear as bright yellow while spelter will show a silvery scratch. The word "pewter" is thought to be derived from the word "spelter". Zinc ingots formed by smelting might also be termed spelter. Spelter Spelter, while sometimes used merely as a synonym for zinc, is often used to identify a zinc alloy. In this sense it might be an alloy of equal parts copper and zinc, i.e.
Alkali metal is very useful as a heat-exchange liquid in fast breeder nuclear reactors due to its low melting point, viscosity, and cross-section towards neutron absorption. Potassium compounds are often used as fertilisers as potassium is an important element for plant nutrition. Potassium hydroxide is a very strong base, and is used to control the pH of various substances. Potassium nitrate and potassium permanganate are often used as powerful oxidising agents. Potassium superoxide is used in breathing masks, as it reacts with carbon dioxide to give potassium carbonate and oxygen gas. Pure potassium metal is not often used, but its alloys with