Heise: Chloride of Lime 



Time in hours. 



23 



1 .iter TCit i 



«j „ ***~' -»». 



FIG. 2. The decomposition of chloride of lime in distilled water in the dark. 



The data at hand for the progressive decomposition of chloride 

 of lime do not show clearly the order of reaction. The decom- 

 position in sewage is probably a heterogeneous reaction. (17) 

 Fig. 1 shows that for a time the reaction velocity was practically 



constant (^=# ; 1j:=|). 



The decomposition rate of calcium hypochlorite solution in the 

 light. — In the light the decomposition more nearly approached 

 the typical rate of a monomolecular reaction. The data obtained 

 in a typical series of determinations are given in Table II and 

 are plotted in fig. 3. Comparison with fig. 1 shows clearly the 

 difference between the course of the dark and the light reaction. 

 As indicated in the curve, the photochemical decomposition pro- 

 ceeded in a regular manner. As the experiments were performed 

 in the diffused light of the laboratory, the light was a variable 

 factor and caused deviations from the true course of the pho- 

 tochemical decomposition. 



It is interesting to note in this connection that in measurements 

 of the decomposition of chloride of lime in different waters in 

 the dark and in the light the differences between the amounts 

 decomposed in the light and in the dark were very uniform for 

 any given light intensity, regardless, within the limits observed, 

 of the specific chlorine-binding power of the various waters used. 

 This is evident from the data in Table III. The last column 

 shows that for any one day the differences between the "light" 

 and "dark" determinations were nearly the same, though the 

 waters under observation varied widely in their ability to de- 

 compose chloride of lime in the dark. 



