CHAPTER XII GASEOUS AND LIQUID FUELS 250 Gaseous and Liquid Fuels--Coal Gas--All-oil Water Gas--Pintsch Gas--Blau Gas--Water Gas--Measurement of Gas--Gas Meters How to Read the Index--Prepayment Meters--Gas-service Rules--Gas Ranges--Lighting and Heating with Gasoline--Gasoline--Kerosene--The Cold-process Gas Machine--The Hollow-wire System of Gasoline Lighting and Heating--Mantle Gas Lamps--Open-flame Gas Burners--The Inverted-mantle Gasoline Lamp--Portable Gasoline Lamp--Central Generator Plants--Central-generator Gas Lamps--Boulevard Lamps--Gasoline Sad Irons--Alcohol Sad Irons--Alcohol Table Stoves--Danger from Gaseous and Liquid Fuels--Acetylene-gas Machine--Types of Acetylene Generators--Gas Lighters--Acetylene Stoves. CHAPTER XIII ELECTRICITY 305 Incandescent Electric Lamps--The Mazda Lamp--Candlepower--Lamp Labels--Illumination--The Foot-candle--The Lumen--Reflectors--Choice of Reflector--Lamp Transformers--Units of Electrical Measurements--Miniature Lamps--Effects of Voltage Variations--Turn-down Electric Lamps--The Dim-a-lite--Gas-filled Lamps--Daylight Lamps--Miniature Tungsten Lamps--Flash Lights--The Electric Flat-iron--The Electric Toaster--Motors, Fuse Plugs--Electric Heaters--Intercommunicating Telephones--Electric Signals--Buzzers--Burglar Alarms--Annunciators--Table Pushes--Bell-ringing Transformers--The Recording Wattmeter--To Read the Meter--State Regulation of Meter Service--Electric Batteries--Battery Formation--Battery Testers--Electric Conductors--Lamp Cord--Portable Cord--Annunciator Wire--Private Electric Generating Plants--Storage Batteries--The Pilot Cell--National Electrical Code--Electric Light Wiring--Outlet Boxes--Automatic Door Switch--Plug Receptacles--Heater Switch, Pilot and Receptacle--Service Switch--Local Switches--Pilot Lights--Wall and Ceiling Sockets--Drop Lights. INDEX 385 MECHANICS OF THE HOUSEHOLD CHAPTER I THE STEAM HEATING PLANT The use of steam as a means of heating dwellings is common in every part of the civilized world. Plants of all sizes are constructed, that not only give satisfactory service but are efficient in the use of fuel, and require the minimum amount of attention. The manufacture of steam heating apparatus has come to be a distinct industry, and represents a special branch of engineering. Many manufacturing companies, pursue this line of business exclusively. The result has been the development of many distinctive features and systems of steam heating, that are very excellent for the purposes intended.