148 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 4 



13 feet high and with a capacity of 31,122 cu. ft. had six coils with a 

 radiating surface of 386 sq. ft., and these were placed the same as those 

 on the second floor. The fourth floor which was 18 feet high and with 

 a capacity of 43,092 cu. ft., had only five coils with a radiating surface 

 of 322 sq. ft. These pipes were arranged like those on the second and 

 third floors. 



TABLE SHOWING THE DIMENSIONS AND HEATING SYSTEM OF THE MILL 



This mill was badly infested with all stages of Tribolium confusum, 

 and slightly infested with several of the other common mill insects. 

 In the first. experiment no change of any sort was made in the heating 

 system. Four thermometers were distributed on each floor in such 

 a manner as to get the temperature not only in the open, but in dif- 

 ferent depths of flour, and in accumulations in different parts of the 

 room. At 10 o'clock a. m., August 21, with the mill just as it had been 

 shut down for Sunday, the steam was turned into the pipes, and since 

 this mill was ordinarily heated with exhaust steam, the live steam 

 had to be forced through the exhaust pipe, which prevented it from 

 having more than two or three pounds pressure. The heat was applied 

 from 10 a. m. to 5.30 p. m., and the temperatures of all the thermome- 

 ters noted at intervals of every half hour. Although the day was very 

 warm, reaching a maximum temperature of 95°, and the average 

 temperature of the mill before the heat was applied was 89°, yet the 

 mill did not heat rapidly, and by 5 o'clock there were only two or 

 three places in the mill where a fatal temperature had been reached. 

 On the first floor the highest temperature was 100.4°, while one ther- 

 mometer in the bottom of an elevator boot registered only 94°. 



