Little Miracles 31 



stay clean for eight or ten weeks. But in pre-Precipitron days 

 the curtains had to be laundered every two or three weeks. 

 Walls that had to be washed every spring now stay clean for 

 three years or more. This means that paint will last longer, and 

 the savings in laundry and dry-cleaning bills also add up to 

 quite a sum. 



However, the air leakage into the average house is far 

 greater than most of us realize. Penney says that the air in 

 most houses will be changed from one to two times per hour 

 due to normal leakage around doors, windows, flooring. This 

 will limit the efficiency of the Precipitron and any air-condi- 

 tioning unit. But the performance of Penney 's "air laundry" 

 in Pittsburgh's famous smog (smoke plus fog) proves that it 

 is more than just another interesting gadget. After the war it 

 is possible that Precipitrons may cost little if any more than 

 electric refrigerators. Westinghouse has already made a unit 

 that sells for three hundred dollars, and one hundred and fifty 

 of them have been installed in private homes. The company 

 reports that, with large-scale distribution later on, the price 

 will be considerably lowered. 



Smokeless Furnaces 



Another victory over city dirt (as well as over the high 

 cost of heating homes) has been won by Julian R. Fellows, 

 professor of mechanical engineering, and J. C. Miles, asso- 

 ciate, of the University of Illinois. They have developed a 

 furnace of the future to burn soft coal without filling the air 

 with smoke or soot. 



More than 90 per cent of all the smoke produced by even 

 the most volatile of soft coals is consumed by the furnace, 

 which makes it possible to reduce fuel consumption by as 

 much as 25 per cent and to use cheaper grades of coal. Smoke 

 is forced down through the fire, where it is burned. Only the 



