THE INTERACTION OF CHLORIDE OF LIME WITH THE NORMAL 

 CONSTITUENTS OF NATURAL WATERS AND SEWAGE " 



By George W. Heise 



FIVE TEXT FIGURES 



(From the Laboratory of General, Inorganic, and Physical Chemistry, 

 Bureau of Science, Manila) 



In the course of an extensive study of the sterilization of 

 water and sewage, parts of which have already been reported, (9) 

 it became necessary to do considerable work on the decomposi- 

 tion of chloride of lime (calcium hypochlorite) in water and 

 on its interaction with waters and sewage. The work was done 

 because of its practical importance, and no attempt was made 

 to study in detail the chemical reactions involved ; the results are 

 presented at this time because of their possible application to 

 sterilization problems involving the use of hypochlorite solutions. 



The value of chloride of lime as a disinfectant was first pointed 

 out by Koch (12) in 1881, while its application on a large scale to 

 the sterilization of water for municipal supply was first proposed 

 in 1894 by Traube. (23) That waters containing hydrogen 

 sulphide or relatively large quantities of organic matter are not 

 readily sterilized with chloride of lime was shown by Lode (14) 

 in 1895. Since that time hypochlorites have been so widely used 

 for the disinfection of water and sewage that their decomposition 

 and their interaction with the substances normally found in water 

 and sewage have been much studied. 



Hypochlorites in distilled-water solution decompose, even in 

 the dark, with measurable velocity. (2) Both chlorate and 

 oxygen are formed, although the main reaction proceeds accord- 

 ing to the equation 



2NaC10 -> 2NaCl + 2 . 



The decomposition is accelerated by heat, proceeding in 

 accordance with the equation : (2) 



3NaC10 -> NaCIO, + 2NaCl, and 

 2NaC10 -> 2NaCl + 2 . 



The results of Bhaduri(2) indicate that for certain concen- 

 trations in the dark at 100° C. the reaction is monomolecular, 



1 Received for publication December 1, 1916. 



