248 



LIGHT IN THE HOME 



The tungsten light. - - The old carbon filament is 

 rapidly being replaced by the tungsten lamp. The 



carbon filament can 

 be heated to 1850 

 degrees Centigrade, 

 while the tungsten 

 filament can be 

 heated to 2100 de- 

 grees Centigrade, and 

 in bulbs which are 

 filled with nitrogen, 

 the temperature may 

 go still higher ; there- 

 fore we get a much 

 brighter light from 

 the tungsten lamp. 

 A one hundred candle 

 power tungsten, ni- 

 trogen-filled bulb re- 

 quires only about one 

 seventh as much elec- 

 tricity as the one 

 hundred candle 

 power carbon lamp. 

 The table on the fol- 



GAS OPSN 



GAS 



CARBON ELECTRIC 



Cost, 



EUCTR1C 



5 10 15 20 

 1000 CctTXoLle, 



30 35 

 IT\ 



This chart, suggested by the Bureau of Standards, 

 shows the relative cost of light from different illu- 

 minants, based on the following prices : candles, 

 i2fi a pound; kerosene, 15 i a. gallon; gas, $i per 

 1000 cu. ft.; electricity, io*i per kilowatt-hour. 

 Solid black represents cost of fuel, and shaded, lowinP" naP"P showi 

 cost of mantles and bulbs. Revise this chart in IUW1I1 5 P d 5 e 

 your notebook to agree with cost of these illumi- some common liffht 

 nants in your own city or town. null iigiit 



intensities. A good 



home project would be to find out the difference in the 

 cost of lighting your home with the fishtail gas flame, the 

 Welsbach gas flame, carbon filament electric lights, and 

 tungsten filament lights. 



