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feet of the gas, this result being further corrected for any divergence of the temperature and pressure of the gas from the normal 60° F. and 30.0" Bar., or in other words the volume of gas burnt must be corrected to 60° F. and 30:0” Bar., and a corresponding proportion be made for any divergence from ten cubic feet at standard temperature

and pressure.

SPENT OXIDE OF IRON TEST.

The amount of free sulphur in spent oxide of iron is arrived at by means of the apparatus shown in Fig. 65, the method of procedure being as follows.

Weigh 100 grains of the material, dry at a temperature of 100° C. and repeatedly weigh until a constant weight is obtained, so as to arrive at the percentage of moisture : then place the dried substance in a, which is packed at the bottom with a plug of cotton wool in order to serve as a filter.

A quantity of carbon bisulphide (CS) is then blown from the bottle Binto a on top of the spent oxide, through which it percolates dissolving out the sulphur, the resulting solution finding its way by gravitation into the flask C, the latter being placed in a water bath which is heated so as to vapourize the carbon bisulphide, the vapour thus driven off, travelling through the connecting tube into the condenser, from whence it is recovered in the flask D (under water) ready for another experiment.

The sulphur is left in the tared flask attached to A, and when all the bisulphide has been driven off, on re-weighing the flask the quantity of sulphur in the 100 grains of oxide taken for experiment will be shown, and this figure will also express the percentage of sulphur on the “wet” basis.

SPECIMEN EXAMINATION PAPERS OF THE CITY AND GUILDS OF LONDON INSTI

TUTE IN GAS MANUFACTURE.

Wednesday, May 2nd, 1894. 7 to 10.

INSTRUCTIONS.

The Candidate must confine himself to one grade only, the Ordinary or Honours, and must state at the top of his paper of answers which grade he has selected. He must not answer questions in inore than one grade.

If he has already passed in this subject, in the first class of the Ordinary Grade, he must select his questions from those of the Honours Grade.

The number of the question must be placed before the answer in the worked paper.

Three hours allowed for this paper.

The maximum number of marks obtainable is affixed to each question.

ORDINARY GRADE,

1. What do you understand by carbonization, and how is it conducted ? (35 marks.)

2. Explain the conditions which are essential to good carbonization. (35.)

3. How are tar and ammoniacal liquor produced ? (25.)

4. In what way is lime employed for the purification of gas? and explain its action. (30.)

5. What is meant by “ 8.oz. liquor ” ? (25.)

6. Describe the ordinary tests for ascertaining the purity of gas. (30.)

7. Describe the method of determining the illuminating power of gas. (30.)

8. Give a sketch of the Referees' sulphur test, and explain its use. (30.)

9. How is condensation usually effected ? (30.)

10. What is a syphon or receiver, and under what circumstances is it necessary to use one ? (30.)

HONOURS GRADE.

1. What is the proportion of gaseous products yielded by ordinary gas coal, and of what does it chiefly consist ? (35 marks.)

2. Give a sectional elevation of the side of a purifier, and explain the reason for a determinate depth of water lute. (30.)

3. How may the presence of nitrogen in coal-gas be accounted for, and what is its effect upon the illuminating power? (35.)

4. Explain the difference between a puddled and a rendered tank, and state how the water-pressure is exerted in each case. (30.) 5. Describe

any method or system by which hand labour in the retort-house may be reduced or dispensed with. (30.)

6. What is the Orsat-Muencke apparatus? Explain its use. (30.)

7. Explain the action of a modern gas-retort furnace, as illustrating the principles of economical combustion. (30.)

8. Why is it usual to free the gas from ammonia before it enters the purifiers ? (25.)

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9. Describe the process for the manufacture of sulphate of ammonia from gas liquor. (30.)

10. Describe a means for obtaining the highest illuminating value from coal-gas. (25.)

GAS MANUFACTURE.

May 1st, 1895.

ORDINARY GRADE. 1. Describe the process of carbonization, and give a sketch and description of a through clay retort.

2. What process immediately follows carbonization ? how is it effected, and with what results ?

3. What is the usual treatment of coal-gas for the removal of ammonia ?

4. Enumerate the chief impurities contained in crude gas, and state how their presence may be detected.

5. Describe a method of freeing gas from sulphuretted hydrogen.

6. What is the use of the exhauster? 7. How is the illuminating power of gas ascertained ? 8. Of what service is the inferential jet photometer? 9. How would you test spent oxide for sulphur?

10. For what purposes are the station meter and governor employed in a gas-works, and how is the latter regulated ?

HONOURS GRADE.

1. Describe the principles of the chief methods of heating gas-retorts.

2. Give an outline sketch (elevation) and description of a setting of eight retorts with fittings.

3. What kinds of coal are most valuable for gas-making and why?

4. Give a sketch (plan, elevation, and section) and description of a purifier, fitted with three tiers of sieves.

5. In what way would you estimate the quantity of ammonia, sulphuretted hydrogen, and carbonic acid in coal

gas?

6. Give a description, with outline sketch, of an untrussed two-lift gas-holder and puddle-tank, and explain the difference between the latter and a rendered tank.

7. Describe a process for manufacturing sulphate of ammonia from ammoniacal liquor, pointing out what precautions should be taken in order to prevent nuisance.

8. Describe some system of stoking machinery, and state what advantages it may have over hand labour.

9. Describe some method of enriching gas other than by means of cannel.

10. What is the difference between a flat-flame burner and an Argand ? In what respects do these differ from an incandescent burner, and what advantages can be claimed for each ?

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