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, (b) 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 (a) copper sulphate solution, (b) silver chloride, (c) ferric chloride solution, (d) silver oxide, (e) zinc sulphate solution, (ƒ) 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.

595. What occurs when ammonia solution is added to nitric acid? What occurs when the product is heated? Give equation for both reactions.

596. Represent by equations the reactions caused by heating (a) ammonium nitrite, (¿) ammonium nitrate.

597. How is nitrous oxide prepared and collected, and what are its properties?

598. A glowing taper was rekindled when placed in a jar which contained either nitrous oxide or oxygen. How could you ascertain with certainty which gas was present?

599. If 100 litres of nitrous oxide at N.T.P. be decomposed into free oxygen and nitrogen, what increase in bulk will occur?

600. How much phosphorus could be burned in 100 litres of nitrous oxide at N.T.P.?

601. Twenty grammes of nitrous oxide were obtained by heating ammonium nitrate, how much of the salt was used?

602. Point out the resemblances between nitrous oxide and oxygen, and state how they may be distinguished (a) by chemical ̧tests, (b) by physical tests.

603. Write an account of the preparation and properties of nitric oxide.

604. What is the weight of 5 litres of nitric oxide at N.T.P.? What volume at N.T.P. will 5 grammes of the gas occupy?

605. How can it be proved that nitrous oxide contains its own volume of nitrogen, and nitric oxide half its volume of nitrogen?

606. If a gas-holder contains when full 25 grammes of oxygen, what weights of nitrous and of nitric oxides will it hold?

607. What volume of nitrogen will be left in each case, by heating potassium in contact with 17 grammes of nitrous and nitric oxides?

608. What occurs when nitric oxide is passed over red-hot copper, and how much will the copper gain in weight when II litres of the gas at N.T.P. are passed over it?

609. Air is passed into 1 litre of nitric oxide standing over water, so long as brown fumes are formed. What gas remains after these have dissolved, and what is its volume?

610. Answer the previous question for oxygen instead of air.

611. Under what circumstances does nitric oxide

(a) extinguish burning phosphorus, (b) support its

combustion?

612. What happens when nitric oxide is passed into solution of ferrous sulphate?

613. What impurities are present in nitric oxide prepared by the action of nitric acid on copper? How is the gas obtained quite pure?

614. Give different methods for obtaining nitrogen trioxide, and state what occurs when it is added to water.

615. What substance is produced when potassium nitrate is heated, and what is the action of dilute acids on the product?

616. What volume of oxygen must be added to 1234 c.c. of nitric oxide, so as to convert it into nitrogen trioxide ?

617. What is the probable composition of a mixture produced by adding 3 volumes of dry nitric oxide to I volume of dry oxygen?

618. How may nitrites be detected in presence of nitrates?

619. What occurs when dry lead nitrate is heated? Give an equation for the reaction, and describe the oxide of nitrogen thus obtained.