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809. How are each of the substances mentioned in the previous question analysed ?

810. What is “vat waste," and what useful products may be obtained from it ?

811. Describe Mond's process for the recovery of sulphur from vat waste, and state the principles in'volved in the process.

812. Describe Hargreaves' process for the manufacture of salt-cake without the use of sulphuric acid.

813. How is black ash treated so as to obtain (a) soda ash, (6) caustic soda, (c) soda crystals (crystallized sodium carbonate)?

814. How is sodium bicarbonate prepared on the large scale ? Is its reaction alkaline, acid, or neutral ? Why is it called an acid salt, and what occurs when it is heated ?

815. How would you make a complete quantitative analysis of (a) salt-cake. (6) soda ash, (c) caustic soda?

816. Describe the process called the ammonia-soda process, and give the reactions on which it depends.

817. Describe the various methods in use for obtaining common salt from (a) sea-water, (6) brine springs, (c) salt beds.

818. How is perfectly pure caustic soda obtained ? What are the chief impurities in the commercial product ?

819. By what reactions are the sodium compounds usually recognised? Name any insoluble sodium salts.

POTASSIUM.

820. What are the chief natural sources of the potassium compounds ? Suggest a process for obtaining potash from felspar.

821. Describe the various methods of Davy, Gay Lussac and Thenard, and Matthiessen, for the preparation of potassium, and state how it is now obtained on the large scale.

822. How did Dittmar and Dewar determine the vapour density of potassium, and what was the result ?

823. How may caustic potash be obtained perfectly

pure ?

824. How is potassium chlorate prepared on the large scale ?

825. How is the presence of potassium nitrate in the soil in certain parts of India accounted for ?

826. Describe the process for the artificial preparation of nitre. By whom and under what circumstances was it introduced ?

827. Describe the experiments of Schlesing and Müntz and of Warington on nitrification, and state the conditions necessary for the success of the process.

828. What are the constituents of gunpowder, and how is it made ?

829. Mention the chief gaseous and solid products obtained by the explosion of gunpowder. How is the formation of each accounted for ?

830. Taking the composition of gunpowder as 75 nitre, 10 sulphur, and 15 charcoal in 100 parts, and assuming that all the carbon is converted into carbon dioxide, and all the nitrogen obtained in the free state, find the volume of these gases at N.T.P. which should be evolved by the explosion of one gramme of the powder.

831. Able and Noble found that i gramme of gunpowder yielded by explosion in a closed vessel 280 c.c. of gases at N.T.P. What volume would they occupy at 2200° C. which is the temperature at the moment of exploding ?

832. A piece of potassium when thrown on yielded enough potash to neutralize exactly 79 C.C. of a solution of sulphuric acid containing 98 grammes H2SO4 per litre. Find the weight of the potassium.

water

833. How are the nitrite and carbonate of potassium obtained, and what are their properties ?

834. How could you prepare potassium carbonate from the bicarbonate, and vice versâ ?

835. What weights of potassium carbonate and of bicarbonate would be required to yield when treated with acid i litre of carbon dioxide at N.T.P. ?

836. How are the potassium salts distinguished from those of ammonium and sodium ?

837. Discuss the reasons for supposing that the salts of ammonia contain a hypothetical metal“ ammonium." What is the so-called ammonium amalgam ?

838. Compare the salts of potassium with those of ammonium, and point out their analogies.

839. What is meant by dissociation ? Describe an experiment which proves the dissociation of ammonium chloride.

840. Describe the preparation of the carbonates and sulphides of ammonium.

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