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562. What are zeolites, and what is the action of hydrochloric acid on them ?

563. What is the action (if any) on silica of (a) sulphuric acid, (6) potash, (c) hydrofluoric acid, (d) sodium carbonate (heated till fused), (e) chlorine ?

564. How is the quantity of silica in a sample of water usually determined ?

565. How would you make a complete. quantitative analysis of potash felspar?

566. Describe Graham's researches which resulted in the discovery of ortho-silicic acid.

567. What is the substance termed soluble glass, and what is the action of hydrochloric acid on a strong and on a weak solution of it?

568. Explain the term “dialysis," “ colloids," "crystalloids.” Classify the following substances into colloids and crystalloids—common salt, sugar, starch, arsenious acid, glue, nitre, and gum.

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COMPOUNDS OF NITROGEN.

569. Give a short account of the history and natural occurrence of ammonia.

570. How may ammonia be prepared (a) by synthesis, (6) from nitric acid, (c) from ammonium salts ?

571. What is the chief commercial source of ammonia compounds ? Describe fully the preparation of salammoniac on the large scale.

572. Represent by equations the action of potash and of quick-lime on ammonium chloride. How much quick-lime is necessary to decompose 147 grammes of ammonium chloride ?

573. A litre of ammonia gas at N.T.P. weighs 0°7619 gramme. Find how much heavier it is than hydrogen, and how much lighter than air.

574. How was ammonia gas first liquefied by Faraday? Describe Carré's apparatus for obtaining ice artificially by means of liquid ammonia.

575. Is ammonia a combustible gas? Describe experiments in support of your answer.

576. What occurs when ammonia gas is passed (@) over heated potassium, (6) into hydrochloric acid, (c) over red-hot fragments of porcelain ?

577. One gramme of water at 14° C. and under a pressure of 760 m.m. absorbs o‘612 gramme ammonia. What weight of ammonium chloride and of lime must be heated to saturate with ammonia a kilogramme of water at the same temperature and pressure ?

578. Electric sparks are passed through 79 c.c. of ammonia gas. What change in volume occurs, and what is the composition by volume of the residue ?

579. What volume of ammonia gas at N.T.P. should be obtained by heating 139 grammes ammonium chloride with quick-lime ?

580. What is the weight of 35 litres ammonia gas at N.T.P. ? When 35 litres of hydrochloric acid gas are mixed with it, what occurs, and what is the weight of the product?

581. Under what circumstances does ammonia burn, and what are the products of combustion ? Find the volume and weight of the products obtained by burning 129 c.c. of the gas at N.T.P.

582. An alkaline solution (which you are told is either potash or ammonia) is saturated with hydrochloric acid and evaporated to dryness. How would you ascertain (a) by physical tests, (6) by chemical tests, the nature of the product ?

583. A gaseous mixture contains ammonia and hydrogen, how can the hydrogen be obtained entirely free from ammonia ?

584. How can ammonia be obtained from nitric acid, and what weight of nitric acid would be necessary to yield 179 c.c. measured at 13° C. and under a pressure of 754 m.m. ?

585. What volumes of hydrogen and nitrogen are contained in 123 grammes of ammonia ?

586. Describe fully Hofmann's method of ascertaining the composition of ammonia, by the action of chlorine on the gas.

587. Seventy-five grammes of a solution containing 21 per cent. of ammonia are added to 134 grammes pure nitric acid. Find the weight of ammonium nitrate produced, and of nitric acid remaining unsaturated.

588. What occurs when ammonia is added to (c) copper sulphate solution, (6) silver chloride, (c) ferric chloride solution, (d) silver oxide, (e) zinc sulphate solution, (f) manganese chloride solution?

589. How is ammonia usually tested for and estimated quantitatively? What is Nessler's test, and how is it used ?

590. How is chloride of nitrogen prepared, and what are its properties ? Name the chemists who discovered it and investigated its properties. What is the most probable formula for the compound?

591. How is iodide of nitrogen obtained ? What views are held with regard to its composition ?

592. How may nitrogen be directly combined with oxygen ? Sketch the apparatus used to show the union.

593. Give a list of all the compounds of nitrogen and oxygen which have been obtained. Give also the formula and density of each, and state whether they are solid, liquid, or gaseous at the ordinary temperature.

594. Electric sparks are passed through a globe filled with air. Ammonia solution is then added to the globe and the product evaporated to dryness. State fully what occurs, and name the oxide of nitrogen which would be obtained on heating the residue.

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