This section is from the book "Materia Medica And Therapeutics Inorganic Substances", by Charles D. F. Phillips. Also available from Amazon: Materia medica and therapeutics.
By saturating moist slaked lime with chlorine gas- CaH1O2 + 2Cl = H1O + CaOCl2 - but as to its exact constitution there is still some difference of opinion. Many chemists, following Balard, consider it to be a mixture of chloride and hypochlorite of calcium, which would correspond to the above formula doubled; thus, 2CaOCl2 = CaCl2 + CaCl2O2, and this, with the addition of two atoms of water, is the formula adopted by Garrod.
Occurs in whitish powder or lumps, having the odor of chlorine, and an acrid, caustic taste; if it contain much chloride of calcium it will be moist. It is unstable in composition, readily giving off chlorine when exposed to the air, and being decomposed by any acid. When pure it is wholly soluble in water, but it generally contains some free hydrate, and is only partially soluble. It has powerful deodorant and bleaching properties, which depend on the presence of chlorine, and the purity-test is directed to estimating the amount of this gas (chlorimetry). Thus, by adding hydrochloric acid to chlorinated lime, chlorine gas is liberated, and this being brought into contact with iodide of potassium sets free an equivalent amount of iodine, which is estimated by hyposulphite of sodium.
Liquor Calcis Chloratoe - Solution of Chlorinated Lime - contains about 13 gr. of available chlorine to each fluid ounce of water.