Among the factors which may lead to inaccuracy of results in the use of some indicator mixtures for the direct determination of soil reaction,the following were studied in the present work:(1) Unequal adsorption of indicators by soils;(2) High proportion of alcohol to water in the indicator mixture;(3) Change of solubility of some of indicators as affected by the acidbase status of the soil and/or by clanging the concontration of alcohol whilo admixing the indicator mixture into the soil suspension;(4) High concentration of indicators themselves;and(5) Other factors such as the effect of high salt concentration,etc.The adsorption of indicator by soil varied with the nature of the indicator as well as that of the soil.Among the indicators studied,methyl red,brom-cresol green,brom-phenol blue and methyl orange wore markedly adsorbed by Red Earths and Brown Forest.Soils.The degree of adsorption by Red Earth followed the order:methyl red>brom-cresol green>brom-phenol blue>methyl orange.Littlo adsorption,however,was noticed in the case of methyl red by Yellow Earth and of brom-cresol green by Chernorem and recent alluvial deposit.