EXPERIMENT STATION BULLETINS. 



506 



connected. For this purpose any kind of hand pump can be used that 

 will force the liquid through under pressure. The gage is an ordinary 

 500 lb. steam pressure gage and is placed on the main line so that the 

 pressure can be read on any cylinder of the battery, by putting in or 

 cutting out the cylinders from the pressure pump. 



The small cylinder (5 inches by 22 inches) is capable of holding 28 to 

 33 lbs. of soil depending upon the nature of the soil, while the larger 

 ones (6 inches by 24 inches) hold 35 to 50 lbs. 



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^w/ re screen 



FIGURE 1. LONGITUDINAL SECTION OF THE SMALL CYLINDER. NOTE THAT WIRE 

 SCREEN (USUALLY 2) OVERLAPS THE PERFORATED PLATE. 



Before using the cylinders the inside is coated with hot paraffin; in 

 order to keep the soil and the solution away from the iron. The lower 

 pipe and spout as well as the plate and gauze in tlie bottom are also 

 treated in like manner. 



The cylinder is weighed before and after filling in order to get the 

 weight of the soil used. The soil used is thoroughly mixed by rolling it 

 back and forth on a large piece of oil cloth. The soil is added in small 

 quantities (about a double handful) at a time, a small portion being 

 saved each time for a composite moisture sample. The soil in the 

 cylinder is thoroughly packed down by means of a stick with an iron 

 disk on the end. A great deal depends upon the packing. If loosely 



