Popular Science Montliljj ,>9I? 



Caging the Airplane Propeller in Kerosene Can Be "Cracked" to Pro- 

 Case He Gets Too Wild duce Gasoline 



IF crude oil yields different liquids when 

 '_ heated to different temperatures, what 

 would happen if the separate distillates 

 were treated again in the same way ? The 

 experiment has been carried out with 

 astonishing results by different chemists — 

 Doctor Burton, Doctor Hall, and Doctor 



R i t t m a n . 



our 

 de- 



this 

 ex- 

 cage 



THE propeller of a modern flying ma- 

 chine rotates at the rate of about 

 fifteen hundred revolutions a minute. It 

 is mounted directly on the shaft of the 

 powerful motor by which it is driven. 

 When the engine is started, the roar is 

 deafening— 

 so much so 

 that in test- 

 ing an air- 

 planepower 

 plant before 

 is mounted in 

 a machine, the 

 men who con- 

 duct the test 

 must wear ear- 

 protectors, 

 similar to those 

 used by the 

 crews of 

 big coast 

 fense guns 



But all 

 does not 

 plain the 

 in which the 

 propeller is re- 

 volved during 

 the test. What 

 is the reason 

 for that? 



The cage is 

 a safety device. 

 It protects the 

 men who are 

 conducting the 

 operation. Fly- 

 wheels of steam engines sometimes burst 

 when they spin too fast. Why? Be- 

 cause of the centrifugal force. The greater 

 the speed, the greater is the centrifu- 

 gal force. A propeller which revolves 

 at the rate of fourteen hundred revolu- 

 tions a minute might fly off, even though 

 the utmost precautions are taken to 

 fasten it securely to the shaft. And if it 

 ever flew off — ? A bursting flywheel has 

 many a time wrecked an engine-house as 

 effectively as a high-explosive shell, and 

 a wild airplane propeller would be most 

 unhealthy for anything it encountered 

 upon its wanderings. The eye extends 

 along the edge of the testing platform. 





© Underwood and Underwood 



Airplane propellers occasionally have their own 

 ideas about flj^ing. This cage discourages them 



Kerosene, for 

 example, can 

 actually be 

 made to give 

 up gasoline. 

 The process is 

 called "crack- 

 ing." Imagine 

 before you two 

 piles of stones 

 of different 

 sizes. The small 

 stone-pile rep- 

 re sents gas- 

 oline, the large 

 one kerosene. 

 A man with a 

 hammer can 

 obviously 

 crack the 

 larger 

 stones into 

 pieces equal 

 in size to 

 those of the 

 first pile. The 

 chemical equiv- 

 alent of this 

 seems to take 

 place in crack- 



ing kerosene. Since kerosene is so difficult 

 to dispose of, why not crack it and get 

 enough gasoline for the four million auto- 

 mobiles which will be in use this year. 

 Cracking processes actually furnished 

 seven and one-half per cent, of the total 

 gasoline production last year. 



In 1918, at least one-fifth of the three 

 billion gallons to be produced will be made 

 by cracking. Their value would pay for 

 ten superdreadnoughts. 



Had it not been for the invention and 

 utilization of cracking processes, gasoline 

 would cost more than it does. During 

 the year 1917, approximately 600,000,000 

 gallons of cracked gasoline were produced. 



