April, '11] dean: fatal temperatures 147 



time the«insects were placed in the incubator was 87°, or the same as 

 the temperature of the place from which they were taken. The behav- 

 ior of the various insects as the temperature gradually increased was 

 most interesting. At 10.45 a. m., with a temperature of 95°, the 

 larvae and adults of Tribolium confusum began to appear uneasy, and 

 their uneasiness increased rapidly with the rise of temperature. At 

 11.45 a. m. with a temperature of 99°, the adults of Ephestia kuehniella 

 began to move and fly about with the same uneasiness. At 2.15 p. m. 

 with a temperature of 110°, all stages of the different insects were most 

 active and were making every effort to escape the heat. Even the 

 pupae were wriggling and struggling. At 3.45 p. m., with a tempera- 

 ture of 116.5°, the first adult of Ephestia kuehniella died, and at 4.30 

 p. m., with a temperature of 118.5°, all the moths were dead, and a 

 few of the adults and larvae of Tribolium, confusum. At 5.15 p. m., 

 with a temperature of 121°, all of the Silvanus. surinamensis were 

 dead, but two adults and five larvae of Tribolium confusum were alive. 

 At 5.30 p. m., with a temperature of 122°, two larvae of Tribolium con- 

 fusum were still alive, but these died eleven minutes later at a tem- 

 perature of 122.5°. In this experiment fifteen insects of each stage 

 were used. (Chart I.) 



The Heat Method Put to a Test in a Modern Mill 



Since the laboratory experiments demonstrated that this class of 

 insects could be destroyed at a temperature not beyond that which 

 could actually be produced within a modem mill, a flour mill was 

 selected for a practical test. This mill had heavy^ brick walls and 

 tight wooden floors. It had no basement, was four stories high, all 

 stories were heated with steam, and were well filled with machinery'. 

 The packers, elevator boots, and pulley machinery were on the first 

 floor; the rolls were on the second floor, and the purifiers, sifters, 

 and bolters were on the third and fourth floors. It had a daily ca- 

 pacity of 600 barrels, and in its construction represented the average 

 modern mill in the state of Kansas. The first floor, 38 feet wide, 

 63 feet long, and 12 feet high, A\dth a capacity of 28,728 cu. ft., was 

 heated by eight one and one-half-inch steam pipes, the radiating sur- 

 face of which was 515 sq. ft. These pipes were arranged in eight coils 

 near the ceiling along the two sides and across one end of the room. 

 The pipes were placed near the ceiling in order not to obstruct the 

 doorways. The second floor, the capacity of which was the same as 

 that of the first, had one coil less of the steam pipes Avith a radiating 

 surface of 450 sq. ft., but these seven coils were placed near the floor 

 along the side walls and across one end. The third floor which was 



