Soils 



crosses and a two-inch tee, connecting these with nipples forming a header 

 which shall be about four inches shorter than the width of the bench in which 

 the soil is to be sterilized; screw the one-inch pipes into this header firmly, 

 leaving them so that the openings of the drill holes will stand at the sides of 

 the pipe and not up and down. The object of this is to force the steam later- 

 ally through the soil, and not upward. If the hole stands upward the 

 pressure of steam will drive an opening straight through the soil to the sur- 

 face, and the steam will escape through this aperture without penetrating the 

 soil. The accompanying drawings will show better how the header is made 

 than can be conveyed by a description. When this apparatus is completed and 



Header 



placed in the bench, it should be connected with the steam main by a two- 

 inch pipe. A right and left coupling, or a union, may be used to connect 

 with the steam pipes. When finished, this will make an apparatus that will 

 sterilize the soil in thirty to forty feet of bench, according to the lengths 

 of one-inch pipe used. Place the apparatus in the bottom of the bench, and 

 fill the remainder of the bench with soil, so that the entire machine is fully 

 covered to a depth of six to seven inches, extending ten to twelve inches be- 

 yond the ends of the pipes. Now cover the surface of this soil with old gunny 

 sacks, or pieces, of burlap, horse blankets, or any old cloth that may be at 

 hand. A pressure of fifty pounds of steam should be carried upon the boiler 

 at the time of injecting the steam into the soil. Open the valves gradually, 

 and allow the steam to run into the sterilizing machine, lightly at first, increas- 

 ing the pressure so that the entire force of steam will be turned into the soil 

 within one minute from the time the valve is opened. Let this steam blow 

 into the soil for twenty to thirty minutes, after which time it may be turned 

 off and the sterilizing pipes taken out, although these may be allowed to re- 

 main some considerable time if desired. If the boiler is of sufficient capacity 

 to keep up the steam pressure of ten, fifteen or twenty pounds, it will raise 

 the temperature in the soil to about 205 degrees. This is sufficient to kill 

 all of the bugs, earth worms, wire worms and other insects which infest 

 the soil, and to destroy almost all weed seeds and spores of fungi. 



57 



