Apr. 1922] STUDIES in termite control 13 



this provided a small cell 1 in. square and 1-4 in. deep in the center of the block. 

 In the experiments, ten termites were placed in the cell in each test. The 

 halves were then bolted together and the block was placed in a Freas electric 

 oven provided with thermostat control. The block was allowed to remain 

 in the oven for 24 hours at various temperatures, ranging from 155° F. 

 down to 95° F. The tests were started at a temperature of 155° F. 

 and in successive tests this was dropped until a point was reached at which 

 the termites were not killed. It was found that a temperature of 120° 

 F. continued for 24 hours, resulted in the death of all of the termites in 

 three tests, but a temperature of 95° F., continued for 28 hours failed 

 to kill them. The detailed results are given in the following table: 



Temperature Tests 



Killing Effects of Heat on Termites Placed in Center of Spruce Block 



10x10x10 

 No. of Insects Temperature Time Results 



10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 



Following these preliminary tests, arrangements were made for installing 

 supplementary steam pipes in the basement, of sufficient capacity to raise 

 the temperature within the entire basement to 130° F. or more and to main- 

 tain it there. 



In the rear of the basement was a small boiler capable of carrying a steam 

 pressure of 50 lbs. or more, (Fig. 4, A.). A system of pipes was installed 

 connecting with this boiler. Two inch pipes were used, arranged in three 

 horizontal sections of seven pipes each. The pipes were supported on tem- 

 porary brackets about 18 in. below the basement ceiling. They were ar- 

 ranged with only sufficient slope to drain off condensation. Each section 

 extended the length of that part of the basement in which it was placed. 

 The general arrangement of the system is^showoi in Fig. 4. The total amount 

 of radiation surface was 700 feet, or about one foot to each 20 cubic feet of 

 space in the basement. 



A preliminary test was made and the system was found to be in good work- 

 ing order. The following day, at 6.00 p. m., steam was let into the pipes 

 at a pressure of 40 lbs. Before the steam was turned on, all cracks in windows 

 and doors were sealed with paper. The temperature in the basement just 

 before steam was admitted was 80°. The date was March 22 and the tern- 



