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An examination of methods of extracting calcium oxide from freshly ignited lime by various non-aqueous extracting agents and its determination by potentiometric, volumetric and compkxometric methods has been carried out. New indicators have been recomniended for the visual alkalimetric titration of the extracts. The use of these indicators gives values consistent with those obtained by potentiometric titrations.Various factors, such as the ratio of the extractant to alcohol in the titration medium, the percentage of water that can be tolerated therein and the possibility of using industrial methylated spirit, have been examined. These factors can be a source of error in :such determinations. DETERMINATION of "free lime" in lime and silicate products, such as cements, pozzolanas, mortars and concrete, is very often required in the evaluation of these materials. In the past, many methods have been developed and have also been critically examined for their accuracy. The chemical methods for the deterrnination of "free lime" involve essentially the extraction of "free lime" by aqueous or non-aqueous solvents and then the determination of the calcium oxide content of the extract by a suitable titration method.Several aqueous solvents, such as lime watt:r,l dilute and weak acids, solutions of an ammonium salt2 and sugar,3 have been used. 14s with these extracting agents there is a likelihood of increase in the extracted calcium oxide content caused by hydrolysis of the silicate: the use of non-aqueous solvents has been preferred to that of aqueous solvents.Of the several non-aqueous extracting agents, glycerol was suggested by Emley5 and its use was re-examined by a number of workers. The extracted lime was titrated against am-

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