EXPEKIMEXT STATION BUELpyriNS. GSa 



days a sample was taken from the soil, air-dried, and its freezing point 

 depression determined by using 15 grams of air dry soil with 10 c.c. of 

 water. 



In the first procedure it was desired to ascertain the rate and extent 

 of solubility of soils at a lalher high moisture content or when there was 

 plenty of free water present, so that when the soil had thoroughly set^ 

 tied in the tube there would be a thin layer of free water at the top of 

 the soil column. 



In the second procedure it was desired to attain the same object when 

 the moisture content was maintained at the optimum content and thus 

 under more practical conditions. 



In a limited number of experiments a tliird procedui'e was also followed. 

 In order to study more extensiveh' the elfect of the mass law or the 

 relative masses of soil and water upon the solubility of soils 5 grams of 

 soil were placed in the freezing tube and washed several times by de- 

 cantation. Then to this washed soil was added about 25 "c.c. of dis- 

 tilled water so that the ratio of soil to water was about 1 to 5. The 

 rate and extent of solubility of soils at this high water content were 

 measured in the same manner as in the other studies. 



The rate and extent of solubility of soils at these various moisture 

 contents were measured at dilferent temperatures. On the whole, only 

 three sets of temperatures were employed (1) below freezing, 20'' (room 

 temperature) and 53 °C. The results at below freezing were obtained 

 <mtdoors during the winter months, and those at 53° C in a constant 

 temperature oven. 



The soils at the optimum moisture content were kept nidstly (ititdi.'ors. 

 In fact, an attempt was made to simulate as much as possible the prac- 

 tical or field conditions. 



The tubes containing the soils at the high moisture contents were kept 

 stoppered, but in order to avoid the accumulation of any gases and 

 especially carbon dioxide, they were opened very often and the soils 

 were stirred and thoroughly aerated. 



The freezing point apparatus employed was practically the same as that 

 used in former investigations and described in previous publications.' 

 It consisted briefly of two parts, a bath and a Beckmann thermometer. 

 Tlie bath was composed of two earthen-ware jars placed one inside the 

 other and well insulated. Its temperature was maintained at about -2° 

 by means of crushed ice and common salt. 



The freezing point lowering was determined hj placing the tube con- 

 taining the soil directly into the cooling mixture and stirred the soil 

 constantly by means of the Beckmann thermometer until the temperature 

 fell to about 1° above the zero point of the thermometer. Then the soil 

 was allowed to remain undisturbed until its temperature fell to about 

 0.5° below the zero point of the thermometer when the soil was again 

 stirred by means of the thermometer in order to cause solidification to 

 take place. As soon as solidification commenced the tube was at once 

 taken out of the cooling mixture and placed in the air jacket in the same 

 bath. The soil was genth- stirred, the thermometer tapped and tlie 

 freezing point read by. means of a lens. By this procedure it took onlv 

 about ten minutes to make a freezing point determination. 



(1) Mich. Agri. Expt. Sta. Fed. Bill. 31, 1916. 



