Heise: Chloride of Lime 



29 



fig. 4, the experimental data from Glaser's(5) Table XXIX for 

 20-hour digestion periods being inserted for comparison. For 

 use in this figure, the data in Table VI were recalculated as parts 

 per million. 



Available chlorine added. Parts per million. 



.*UC 2tt>l 





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Fin. 4. The decomposition of chloride of lime in sewage in the dark. Curve a, results 

 of Glaser ; curve b, Table VI, series 4 ; curve c, Table VI, series 7 ; curve d, Table 

 VI, serie, 8. 



Effect of the concentration of substances reacting with chloride 

 of lime. — The more concentrated the solution with which the 

 chloride of lime reacts, the more chlorine is used up. This is 

 to be expected, and it has been pointed out so often that it needs 

 no further proof here. There is, however, a curious anomaly 

 which may occur and which may lead to confusion in the inter- 

 pretation of the ordinary laboratory tests of the chlorine-binding 

 power of a water. The interaction of urea and chloride of lime 

 in the dark at moderate temperature furnishes an illustration 

 of this, when the decomposition of chloride of lime is measured 

 in the usual manner, that is, by means of standard sodium 

 thiosulphate, in the presence of potassium iodide, phosphoric acid, 

 and starch. 



In Table VII are the results obtained when the same quantity 

 of chloride of lime was allowed to react with different quantities 

 of urea. They show that, for very low concentrations of urea, 

 increase in concentration leads to increased chlorine consump- 

 tion ; with higher concentrations, however, the chlorine con- 



