The tin must be charged with a mixture of two parts green sulphate of iron and one part lime.  The lime should be slaked a short time before use.  The sulphate, lime, and sufficient water to moisten the whole are ground into a pulp and left to dry.  The dry mixture, which has a reddish-yellow colour, is broken up fine.  Put tray B1 into place and spread half the chemical over it; then lay B on the top and cover it with the remainder.  The lid joint is sealed by a broad rubber band.

While passing through the tin, the ammonia, sulphuretted hydrogen and carbonic acid gases all combine with the chemical, and fairly pure gas issues from the outlet.

The Gasholder.—­As the gasometer is an important feature of a gasworks, our small plant should contain its counterpart, as it serves to regulate the pressure of the gas, and, therefore, the steadiness of the flame, as well as affording storage room.

As a gasometer, one may use a container made on the principle of the lung-testing apparatus described on p. 361; or the gasholder of a lantern acetylene apparatus, which must, of course, be suitably counterweighted.

Working the Plant.—­When starting up the plant, leave the burner open until inflammable gas issues, so that the air present in the various chambers may be displaced.

[Transcribers note:  Premature lighting of the burner may cause the flame to propagate into the system and explode.  I speak from experience.]

INDEX.

Aeroplane, model, self-launching. 
Bedplate for engine. 
Bellows, double. 
Bench, joiner’s. 
Benham’s harmonograph. 
Bicycle shed. 
Boilers, model. 
Bookstand. 
Box kites.

Cabinets, cardboard, cigar-box, match-box, tool. 
Circles, rolling. 
Clock, electric alarm. 
Colour top. 
Cylinder, double-acting steam.

Developing sink. 
Doors for shed. 
Double-acting horizontal steam engine. 
Double bellows.

Eccentrics. 
Electric alarm clock. 
Electric motor, reciprocating. 
Electric railway. 
Engine, hot-air. 
Experiments, apparatus for simple scientific.

Fuels for model boilers.

Gasworks, miniature. 
Ganges, rain, water,
Gimbals, or universal joints. 
Gliders, paper. 
Goold’s harmonograph. 
Governor for engine.

Harmonographs. 
Hot-air engines. 
House ladder.

Joiner’s bench.

Kettles, quick-boiling. 
Kites, box. 
Kite winders.

Ladder, house. 
Lamp, signalling. 
Locomotive, electric. 
Lung-testing apparatus. 
Magic swingers.
windmill. 
Match-boarding. 
Match-box, self-supplying. 
Morse code. 
Morse sounder. 
Motor, electric. 
Motor, water.

Nozzle for steam turbine.

Pantograph. 
Pendulums for harmonograph. 
Pens for harmonograph. 
Pneumatic puzzle. 
Poultry house. 
Propellers for aeroplane. 
Pumps. 
Puppets, wrestling. 
Puzzle, pneumatic.