44 



Percolation of vaier through different soils. 



Description of apparatus. — This apparatus (fig. 5), consists of soil tubes similar to 

 those used for the study of the rate of air movement through soils differing only in 

 having tubes at the top by which the series may be connected by pieces of rubTaer 

 tubing and supplied automatically with water so that the head or pressure in all the 

 tubes can be kept constant. The tubes are filled in the same manner with soil as for 

 studying air movements, and the rate of percolation depends upon the same physical 

 properties of the soils as in the case of the movement of air. 



Details of (he practicum. — 



1. Bee that the water supply is properly arranged. 



2. Tare the glass or cylinder of each soil tube and record its weight in the jiroper 

 place in a table like the one shown below, but do not return them immediately imder 

 the drain tubes. 



3. Remove corks from drain tulies and insert wii-e drips. 



4. When water drops from all the wires, place the glasses and cylinders quickly 

 under the drain tubes, noting the time. 



Fifj. 5. — Apparatus used to stnriy poroolatioii of water through soils. 



5. At the end of 45 minutes quickly remove glasses and cylinders. 



6. Remove wire drips and insert corks in drain tubes. 



7. Weigh glasses and (cylinders with contents and record weights in the proper 

 place in the table. 



8. Make proper computations and introduce results in table. 



Soil. 



Number Weight l^ei^^^t of 

 cyhnder.' cylinder : '"J^ms 



Clay I 



Clav loam 



Sandy \ 



Peat I 



I 



Weight 

 of water 

 percolat- 

 ing in 4.5 

 minutes. 



Average 

 percola- 

 tion in 45 

 minutes. 



Relative 

 rates of 

 perco- 

 lation. 



Tons per 

 acre 



per hour 

 perco- 

 lating. 



Inches 



per hour 



l>erco- 



latfng. 



