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PACIFIC SCIENCE, VoL XX, October 1966 
which resulted in the loss of ammonia upon 
removal of the excess salt. 
4. It is suggested that the amount of ex- 
changeable bases should be expressed in terms 
of percentage of the permanent charges, since 
the pH-dependent charges were considered not 
to take part in the exchange reaction under 
normal soil conditions. 
REFERENCES 
Coleman, N. T., and A. Mehlich. 1957. The 
chemistry of soil pH. In: Soil. The Yearbook 
of Agriculture 1957, pp. 72-79. EJSDA, 
Washington. 
De Kimpe, G, M. C. Gastuche, and G. W. 
Brindley. 1961. Ionic coordination in 
aluminosilicic gels in relation to clay mineral 
formation. Am. Minerol. 46:1370-1381. 
Iimura, K. 1961. Acidic property and ion ex- 
change in allophane. Clay Sci. 1:28-32. 
Iler, R. K. 1955. The Colloid Chemistry of 
Silica and Silicates. Cornell Univ. Press, 
Ithaca. 
Mehlich, A. I960. Charge characterization of 
soils. Trans. 7th Intern. Congr. Soil Sci. II: 
292-302. 
Schofield, R. K. 1949. Effect of pH on elec- 
tric charges carried by clay particles. J. Soil 
Sci. 1:1-8. 
Vanselow, A. P. 1932. Equilibria of base- 
exchange reaction of bentonites, permutites, 
soil colloids, and zeolites. Soil Sci. 33:95- 
113. 
