A text-book on chemistryFor the use of schools and colleges . t thrownupon water, Fig. 282, takes fire, and burnswith a beautiful pink flame. In the air itspeedily tarnishes, as is seen on cutting amass with a penknife; and even in contactwith ice there is decomposition with flame. In thesecases the combustion arises from the hydrogen unitingwith the oxygen of the air and reproducing water, thepotassium simultaneously burning into potassa. Potas-sium is used for obtaining other metals, as aluminum,magnesium, etc., from their oxides. Potassium and Oxygen. There are three oxides of potassium—a s
A text-book on chemistryFor the use of schools and colleges . t thrownupon water, Fig. 282, takes fire, and burnswith a beautiful pink flame. In the air itspeedily tarnishes, as is seen on cutting amass with a penknife; and even in contactwith ice there is decomposition with flame. In thesecases the combustion arises from the hydrogen unitingwith the oxygen of the air and reproducing water, thepotassium simultaneously burning into potassa. Potas-sium is used for obtaining other metals, as aluminum,magnesium, etc., from their oxides. Potassium and Oxygen. There are three oxides of potassium—a suboxide, aprotoxide, and a peroxide; K2 O, KO, and KOz. Suboxide of Potassium, IT20=869 is formed by heating potassium in a limited amount ofair. It takes fire when heated, and is converted by wa-ter into potassa, hydrogen being evolved. What interferes with the productiveness of the operation ? Whatare of potassium ? How does it act on the surfaceof water? Of what use is potassium? How many oxides does itform ? How is the suboxide formed ?. HYDRATED OXIDE OF POTASSIUM. 315 Protoxide of Potassium, K0=41, is made by heating one atom of potassium with one ofhydrate of potassa, K+KO, IIO=.2KO+H. Hydrated Oxide of Potassium, KO, HO=:56, is best procured by boiling two parts of pure carbonateof potassa with twenty of water, and, having previouslyslacked one part of quick-lime with hot water, the creamwhich it forms is to be added by degrees, and the wholeboiled. The process should be conducted in an ironvessel, to which a lid can be adapted, so as to excludethe air during cooling. The resulting carbonate oflime settles, and the hydrate may be obtained by evap-orating the solution rapidly in a silver vessel, pouringout the melted residue on a silver plate, or casting it inthe form of small cylinders. The decomposition which takes place is very simple: KO, C02+ CaO, HO= CaO, C02+KO, HO; that is, the lime takes carbonic acid from the carbonateof potassa, and the oxide
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