46 



The Philippine Journal of Science 



1916 



The following data were secured when samples were digested 

 in the cold : 



Table X. — Effect of digestion at room temperature. 



[Distilled water, 200 cubic centimeter samples, digested four hours at 30° C, titrated hot.] 



Available 



chlorine 



added (parts 



per million). 



Perman- 

 ganate 

 required. 



Errors in- 

 volved in 

 terms of the 

 oxygen-con- 

 suming 

 power (parts 

 per million) . 





 5 

 10 



ec. 

 10.55 

 9.25 

 8.6 







0.65 



1.0 



The errors recorded in this last series are of the same order 

 of magnitude as those previously mentioned (Table IX) ; hence 

 the action of hypochlorite on organic matter proceeds at mod- 

 erate temperature as well as at high temperature. 



That the hypochlorite reacts with the organic matter and that 

 its effect can be only partially eliminated by boiling with sul- 

 phuric acid according to the equations 



CaCla- Ca(0Cl)2 + 2H2SO4 = 2CaS04 + 4HC1 + 20 and 4HC1 + 20 ^ 2H2O + 4C1 

 are indicated by the following data, which resulted on boiling 

 chlorinated samples with sulphuric acid for fifteen minutes 

 before digesting with permanganate : 



Table XI. — Effect of boiling with sulphuric acid in presence of hypochlorites. 







Errors in- 



Avail- 





volved in 



able chlo- 



Perman- 



terms of the 



rine added 



ganate 



oxygen-con- 



(parts per 



required. 



summg 



million) . 





power (parts 

 per millon). 





cc. 





0.0 



11.9 



0.0 



2.0 



11.1 



0.4 



8.0 



10.9 



0.5 



0.0 



10.4 



0.0 



8.0 



8.0 



2.4 



0.0 



12.0 



0.0 



1.0 



11.6 



0.2 



1 



The hypochlorite changes partially to chlorate even in acid 

 solution at boiling temperature. Thus a hypochlorite solution 

 equivalent to 5 milligrams of available chlorine, boiled with sul- 

 phuric acid for five minutes, still had the power to oxidize 0.9 

 milligram of oxalic acid. 



