LABORATORY PRACTICE 



and weigh again. Then place the dish containing the soil in the 

 water oven and leave it four hours for the soil to dry. Cool and 

 weigh at once so there may be as 

 little absorption of water from the 

 air as possible. From the loss of 

 weight, calculate the per cent of 

 hydroscopic moisture in the soil. 

 Place the crucible containing the 

 dry soil in a muffle furnace and 

 leave until all of the organic mat- 

 ter is volatilized. After the cru- 

 cible has cooled on an asbestos 

 mat, weigh and calculate the per 

 cent of volatile matter. The vola- 

 tile matter consists of organic mat- 

 ter and water that is held in chemi- 

 cal combination with the silicates. 

 (Soils from the students' home 

 farms are to be used in Experi- 

 ments Nos. i, 2, 4, 6, 9, 12, 16, 18, 

 19, and 21, each student working 

 with his own soil.) 



FlG> 



5 ^ Muffle Furnace used for de- 

 termining Volatile Matter. 



Experiment No. 2 



Determination of the Capacity of Loose Soils to absorb Water 

 To 100 gms. of air-dried soil in a beaker add 100 cc. of water. 

 Mix the soil and water, then pour the mixture on a saturated 

 but not dripping filter paper fitted into a funnel. For transfer- 

 ring the soil, 50 cc. more water may be used. Measure the drain 

 water in a graduate. To prevent evaporation, keep the moist soil 

 in the funnel covered with a glass plate. Deduct the leachings 

 from the total water used. Calculate the per cent of water retained 

 by the air-dried soil. 



