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524. A sample of coal-gas contains in 100 volumes 45°58 hydrogen, 34'90 marsh-gas, 6:64 carbonic oxide. Find the volume and weight of carbon dioxide and water produced when a litre of it is burned.

525. What compounds are given off when a paraffin candle and coal-gas are separately burned in air?

526. Explain the construction of a Bunsen lamp. Why does the flame not blacken a cold porcelain plate held

over it?

527. A soap bubble inflated with coal-gas is allowed to ascend through the air into a bell-jar filled with hydrogen. What occurs when it reaches the hydrogen ?

528. Explain the principle and construction of the Davy lamp.

529. Describe experiments which show that the inner portion of a candle or gas-flame contains unburnt

gases.

530. How may carbon be directly combined (a) with hydrogen, (6) with oxygen ?

531. Give various methods for the preparation of carbon monoxide. Represent the reactions by equa-' tions.

532. What weight of crystallized oxalic acid is needed

to furnish 17 grammes of carbon monoxide, and what volume of carbon dioxide at N.T.P. would be likewise obtained ?

533. How may carbon monoxide be obtained from carbon dioxide, and vice versâ ?

534. Explain the production of carbon monoxide when coals burn in an ordinary fireplace.

535. How may carbon dioxide be separated from carbon monoxide and vice versâ ?

536. One gramme of carbon is heated in contact with 119 litres of carbon dioxide at N.T.P. What reaction occurs, and what is the volume after the experiment?

537. You are required to prepare (a) pure carbon dioxide, (6) pure carbon monoxide, using only carbon and oxygen. How will you proceed in each case ?

538. What volume of oxygen when exploded with 120 c.c. carbon monoxide is just sufficient to cornbine with it, and what volume of carbon dioxide is produced ?

539. What weight of carbon is contained (a) in a litre of carbon monoxide, (b) in a litre of carbon dioxide, and how could you obtain it from each gas?

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540. Give two distinct ways for obtaining carbon dioxide from marble (carbonate of lime), and describe the properties of the gas.

541. What occurs when carbon dioxide is (a) heated with potassium, (6) shaken up with litmus solution, (c) allowed to pass through solution of caustic potash ?

542. What is lime-water, and how is it made? What happens when carbon dioxide is led into it (a) in small quantity, (b) in excess ? Express all the reactions by equations.

543. How is carbon dioxide obtained as a liquid and as a solid ?

544. Explain the term “temporary hardness” applied to water. What occurs when such water is boiled ?

545. A diamond weighing oʻ1247 gramme and containing o`03 per cent. of ash is burned in oxygen. Find the volume and weight of carbon dioxide produced.

546. A closed room has a capacity of 27 cubic metres. Find the weight of oxygen, nitrogen, and carbon dioxide it contains, before and after a kilogranıme of pure carbon is burned in it.

547. Dumas and Stas found that 300'02 parts of diamond combine with 800 parts of oxygen to form

carbon dioxide. Calculate from these data the combining weight of carbon.

548. What are petrefactions, and how have they been formed ?

549. What is the formula for carbonic acid ? What occurs when its aqueous solution is (a) boiled, (6) added to litmus solution, (c) added to lime water?

550. How did Faraday first obtain carbon dioxide in the liquid state ? What is meant by the “critical point” of a gas? How did Andrews ascertain the critical point of carbon dioxide ?

551. How does liquid carbon dioxide occur in nature, and how has this been ascertained ?

552. A piece of Iceland spar lost when heated 1'236 gramme. Find its weight, and the volume of carbon dioxide evolved, measured at 13° C. and 755 m.m. pressure.

553. How may carbon be combined with sulphur, and what are the properties of the product ?

554. How much carbon and sulphur are contained in a litre of carbon disulphide (S. G. = 1

1'292), and how could they be obtained from it?

COMPOUNDS OF SILICON.

555. How did Buff and Wöhler first obtain silicon hydride? How may the substance be obtained in the pure state ?.

556. What are the properties of silicon hydride, and how is it most readily prepared ?

557. How is silicon tetrachloride prepared, and what is its action on water ?

558. Represent by an equation the reaction which occurs when a mixture of silica and fluor spar is heated with sulphuric acid. What happens when the product is passed into water ?

559. Name six forms of silica found in nature, and state the composition of the following bodies-felspar, opal, clay, serpentine, garnet, talc, orthoclase, and agate.

560. In what organic bodies does silica occur, and how may its presence in water be ascertained ?

561. Suggest a process for obtaining oxygen from silica,

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