PHYSICAL PROPERTIES OF HAWAII SOILS 
29 
Sodium carbonate gave the best dispersion in every instance. 
Similar results were obtained by Joseph and Snow (W, p. 119), 
working with heavy Sudan soils. Sodium hydroxide was better than 
potassium hydroxide in every instance. The behavior of the two 
alkaline soils, Nos. 2 and 6, is of interest. They dispersed much 
better in distilled water than in ammonia, and even the use of caustic 
10 20 JO 40 50 60 70 10 20 30 
Figure 10. — Graphical comparison of the efficiency of three mechanical dispersing 
devices 
potash did not increase the dispersion obtained in water alone. In 
the case of soil No. 48 (acid), the use of ammonia did not increase 
the dispersion over that obtained with water. 3 
The relative efficiency of the various chemicals is shown graphi- 
cally in Figure 11 for the different soils, as well as the composite 
curve for the averages of all soils. 
The effect of increasing the concentration of a deflocculenl 
(potassium hydroxide) was studied on a typical Hawaii clay. The 
3 Since these determinations were carried out, other investigators have shown that lithium 
carbonate causes an even better dispersion than does sodium carbonate. 
