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MAGNESIUM.

894. What is the composition of the following naturally occurring magnesium compounds, and which are used as sources of magnesium salts ? (a) talc, (6) carnallite, (c) meerschaum, (d) magnesite, (e) asbestos, (f) serpentine, (g) dolomite, (h) kieserite, (i) spinelle.

895. Describe fully the preparation of magnesium (a) on the small scale by Bunsen's method, (6) on the large scale by Deville and Caron's process.

896. How is the crude metal purified and made in the form of wire and ribbon? What is magnesium chiefly used for?

897. What occurs when magnesium is (a) burned in air, (5) placed in boiling water, (c) heated in contact with ammonia or nitrogen, (d) heated in a covered Hessian crucible in an ordinary coal-fire, (e) heated with boron trioxide ?

898. What occurs when solution of magnesium chloride is evaporated to dryness? How is anhydrous magnesium chloride obtained ?

899. How is magnesium sulphate obtained from kieserite and from dolomite ?

900. What is the composition of the precipitate produced by adding a soluble phosphate to a solution of a magnesium salt containing ammonia and ammonium chloride ? What occurs on heating this precipitate ? Give an equation.

901. How are the following magnesium compounds obtained, and what is the composition of each? (a) calcined magnesia, (6) fluid magnesia, (c) magnesia alba.

902. Give an account of Black's experiments on magnesia by which he clearly proved the nature of the difference between carbonated and caustic alkalies.

ZINC.

903. Name the chief ores of zinc, and describe the processes used for its extraction by the Silesian, Belgian, and English processes.

904. What impurities are usually present in commercial zinc ? How may each be detected, and how may zinc be obtained perfectly pure ?

905. Under what conditions of temperature is zinc malleable or brittle ? How is sheet zinc made ?

906. How is the so-called "galvanised iron” made, and what advantages does it possess over sheet iron ?

907. What is the action of acids, alkalies, and water on zinc? What is the copper zinc couple, and what is it used for ?

908. Give the composition of the common alloys, containing zinc. 909. How is zinc oxide made?

Describe the preparation of the chloride and sulphate, and give their properties.

910. How has the vapour density of zinc been determined and with what result ?

CADMIUM.

90. How may the presence of cadınium in ores of zinc be ascertained ?

912. How is the metal cadmium obtained on the large scale ?

913. What occurs when zinc is added to solutions of cadmium salts ?

914. How is cadmium hydrate obtained, what is its formula, and how is it distinguished from zinc hydrate?

COPPER.

915. Name the chief ores of copper, and state from which the metal is most commonly obtained.

916. Describe fully the Welsh process for the extraction of copper from its ores. How is copper extracted at Mansfeld in Prussia ?

917. Describe the processes for assaying copper ores known as the Cornish method and the wet method.

918. What processes have been proposed for obtaining copper from the burnt pyrites of sulphuric acid works?

919. What is the action on copper of each of the following bodies? (a) sulphuric acid, (6) ammonia, (c) nitric acid, (d) chlorine.

920. What happens when steam is passed over copper intensely heated ?

921. How is copper hydride obtained, and what is its formulæ ? What is the action of hydrochloric acid on it ?

922. How are cuprous and cupric oxides prepared ? Give two methods for each.

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