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CHROMIUM,

998. What is chrome iron ore, and how is it treated so as to prepare potassium chromate ?

999. Describe the preparation of the chlorides and oxides of chromium, and state from which the metal may be most easily obtained.

1000. How may potassium bichromate be converted into the chromate and vice verså ?

1001. Give equations for the reactions which occur when each of the following bodies is added to solution of potassium bichromate-(a) silver nitrate, (6) sulphuric acid, (c) potash, (d) sulphuretted hydrogen, (e) sulphur dioxide.

1002. What is the formula for chrome alum? Give two distinct methods for preparing it.

1003. What occurs when the bichromate of potassium and the bichromate of ammonium are separately heated ?

1004. What is chlorochromic acid, and how is it prepared ? What is its action on water? Express the reactions by equations.

1005. Compare the analogous compounds of chromium and sulphur, and name any chromium compounds which are isomorphous with the corresponding sulphur ones.

1006. What happens when a solution of chromic acid is treated with zinc ?

1007. How much oxygen by weight and volume should be evolved by heating 2'98 grammes of potassium bichromate with sulphuric acid, and how much chlorine should be evolved on treating the same quantity with hydrochloric acid ?

1008. What is the composition of the crystalline substance formed by treating potassium bichromate with strong hydrochloric acid ?

1009. What are the most characteristic tests for the compounds of chromium?

IRON.

1010. Write a list of the most abundant compounds of iron found naturally, and state which are used as sources of the nietal.

1011. In what bodies is iron found native? How could you ascertain whether a body contained native or combined iron ?

1012. How is chemically pure iron obtained, and what are its properties?

1013. Describe processes for the assay of iron ores : (a) by the dry method, (6) by means of potassium permanganate.

1014. State briefly how the complete quantitative analysis of an iron ore is made, indicating particularly how the quantities of sulphur, manganese, phosphorus, silica, and iron are ascertained.

1015. Describe how malleable iron is obtained by each of the following processes—(a) by the Catalan forge, (6) by Siemens' process.

1016. How is cast-iron made ? Sketch an ordinary blast-furnace, and explain fully how it is used.

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, (b) 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 process 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

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