Oct. 20, I923 
Soil Reaction in Relation to Calcium Adsorption 
87 
cell is shown in figure 2. The frame holding the six electrode vessels 
is supported by an iron rod passing through a hole over the center of 
gravity. The electrode vessels can be shaken continuously by means 
of the apparatus represented in figure 3. The shaking apparatus is 
operated by an electric motor producing about 120 agitations per 
minute. The hydrogen electrode, shown in figure 4, is constructed on 
the same plan as Hildebrand’s (21). The hydrogen was made electro- 
CZZZIl ... . - . — v 
Fig. i.—D iagram illustrating the arrangement of the electrode vessels on a supporting frame which is 
rotated from below by means of a pulley, thus giving the desired amount of shaking. Each pair, com¬ 
prising electrode vessel and calomel cell, is wired independently and is connected to the potentiometer 
by n utans of its own switch, shown at the right, through the main switch S. The individual switches 
are numbered with Roman numerals, and each corresponding bottle used as electrode vessel is num¬ 
bered with the same numeral. The hydrogen enters at H and is distributed to the six electrode vessels. 
The rate of flow to each is controlled by an ordinary glass stopcock. Water for washing the electrodes is 
admitted from below at W and enters the electrode through the same tube as the hydrogen. 
lytically and obtained compressed in iron cylinders. It was purified in 
a train of saturated solution of HgCl 2 , alkaline pyrogallic acid, alkaline 
permanganate and distilled water. 
SOILS AND OTHER MATERIALS USED 
The general plan was to make an intensive study on one soil and then 
extend certain phases to other soils and other materials. Oswego silt 
loam was selected for the more extended study. The sample was taken in 
southeastern Kansas, where acid soils are more common than in the rest 
of the State. It contained a small amount of calcium and was moder¬ 
ately acid. A characteristic feature of this type of soil is the compact, 
