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ZINC.

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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.

923. Give the formulæ for the chlorides of copper and describe their preparation. What is the action of cuprous

chloride on carbon monoxide ? 924. How is copper sulphate obtained commercially? What occurs (a) when it is heated, (6) when ammonia is added to a solution of it?

925. What is the composition of each of the following bodies ? (a) malachite, () atacamite, (c) verdigris, (a) chrysocolla, (e) Scheele's green.

926. What happens when potassium iodide is added to a solution of copper sulphate ?

MERCURY.

927. How does mercury occur in nature, and how is it extracted by (a) the Almaden process, (b) the Idrian process, (c) the Palatinate process ? Describe the methods employed for assaying mercury ores.

928. How is mercury freed from other metals and obtained pure ? At what temperatures does it freeze and boil ?

929. How did Faraday prove that mercury is volatile at ordinary temperatures ?

930. Starting with mercury, how may the oxides and chlorides of mercury be prepared ?

931. How may calomel be prepa.ed from corrosive sublimate, and what is the antidote to poisoning with the latter?

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