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1017. Explain the theory of the iron blast-furnace, and illustrate by equations the most important reactions which occur in the manufacture of cast-iron.

1018. What is the effect of the hot and of the cold blast on the quality of the cast-iron produced in the blast-furnace ?

1019. What is the difference in composition between grey and white cast-iron? What is the action of acids on each kind ?

1020. What is “spiegeleisen"? How is it made, and what is it chiefly used for ?

1021. How is cast-iron treated so as to obtain wroughtiron? How do they differ in composition ?

1022. What impurities render iron “red-short” and "cold short”?

1023. How is steel made : (a) by the cementation process, (6) by Bessemer's process? Sketch the furnaces required for each method.

1024. Describe processes for the analysis of cast-iron, wrought-iron, and steel. Describe also Eggertz's pro. cess for the determination of carbon in iron and steel.

1025. Give a full account of the properties of iron. What is iron rust, and how is it produced ?

1026. What is meint by the passive condition of iron?

1027. What is the action of dilute sulphuric acid on iron ? What is the cause of the disagreeable odour produced when iron is dissolved in acids ?

1028. Starting with ferrous sulphate, how could you obtain (a) metallic iron, (6) ferrous oxide, (c) iron sesquioxide, (d) magnetic iron oxide ?

1029. How are ferrous and ferric chlorides and sulphates prepared, and by what reactions are ferrous distinguished from ferric compounds ?

1030. How is ferric oxide used in the purification of coal-gas? Explain the reaction and state its advantages over other methods.

1031. State the reactions (if any) which occur when the following reagents are added respectively to ferrous and ferric chlorides-(a) hydrated ferrous oxide, (6) barium carbonate, (c) sodium carbonate, (d) potassium iodide, (e) sulphuretted hydrogen. Give equations.

1032. Find the formulæ of an iron salt which contains in 100 parts 48 oxygen, 24 sulphur, and 28 iron.

1033. The crystallised double sulphate of iron and ammonia contains one-seventh of its weight of iron : find its formulæ.

1034. What volume of hydrochloric acid gas at N.T.P. is required to convert 89 grammes of pure iron into ferrous chloride, and what volume of chlorine at N.T.P. would convert the latter into ferric chloride ?

1035. How is iron alum made? Calculate its percentage composition.

COBALT.

1036. How does cobalt occur in nature? How is the metal prepared, and what are its properties?

1037. What is the colour when anhydrous of (a) cobalt chloride, (6) cobalt iodide? What changes occur on the addition of water to each ?

1038. Give a short account of the ammonio-cobalt bases.

1039. What is the action on cobalt chloride : (a) of potassium nitrite, (b) of potassium cyanide ?

1040. By what reactions is cobalt usually recognised? How is it distinguished from nickel ?

NICKEL,

1041. Give a short account of the metallurgy of nickel. What is its chief use in the arts?

1042. Describe a chemical process for preparing nickel perfectly free froin cobalt.

1043. What is the composition of German silver ?

1044. Compare the properties of nickel and cobalt, and point out the chief differences between them.

1045. It has been suggested that nickel and cobalt are really different forms of the same element. Give reasons for and against this hypothesis.

1046. How may the native sulphides of nickel, cobalt and iron be distinguished from each other?

1047. How is nickel sulphate prepared, and how much of the metal would be required to prepare 798 grammes of the crystallised salt?

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