THE OXYGEN-CONSUMING POWER OF NATURAL WATERS* 



By George W. Heise and R. H. Aguilae 



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



Bureau of Science, Manila, P. I.) 



Although the determination of the oxygen-consuming capacity 

 of a water as measured by its ability to reduce potassium per- 

 manganate is known to have marked limitations, there can be 

 little question that a series of determinations at regular inter- 

 vals is of great value in determining the quality of a water 

 supply, especially when studied in conjunction with bacteriolo- 

 gical data.^ The oxygen-consuming capacity is a sensitive index 

 of the fluctuation in the quality in a water supply, and it is 

 especially valuable because it shows relatively small diiferences 

 rapidly and with some degree of accuracy. 



Many methods for measuring the oxygen-consuming power 

 have been proposed and discussed, among them are the deter- 

 mination in acid solution after digestion with potassium perman- 

 ganate at boiling temperature (Kubel method), the digestion 

 with permanganate in alkaline solution (Schulze method),^ the 

 digestion with acid permanganate at room temperature or at 

 even lower temperatures,* and the digestion with alkaline per- 

 manganate solution at reduced temperatures.* No less than six 

 different procedures for digestion and titration of samples are 

 recorded by the American Public Health Association.® As very 

 slight modifications in method lead to great discrepancies in 

 results, it becomes of interest to study the various procedures, 

 with a view to comparing the results obtained by different 

 methods, as well as for the purpose of studying the factors 

 influencing the determination. 



That the oxygen consumption is not a reliable measure of the 

 organic matter in water has repeatedly been pointed out.* Tie- 

 mann and Preusse,'' in experiments with various substances 

 such as tartaric acid, cane sugar, asparagin, aniline hydrochlo- 

 ride, and the like, found that the oxidation by means of per- 

 manganate was usually less than the value corresponding to the 



* Received for publication December 8, 1915. 

 ' Barnard, Eng. Rec. (1913), 68, 297. 



' Dingier' s polytech. Journ. (1868), 188, 197. 

 'Dupre, Analyst (1886), 10, 188., 



* Winkler, Zeitschr. f. analyt. Chem. (1914), 53, 561. 



' Standard Methods of Water Analysis, 2d ed. New York (1912), 28. 

 ' Flugge, Hygienische Untersuchungsmethoden. Veit & Co., Leipzig 

 (1881), 244. 



' Ber. d. deutsch. Chem. Ges. (1879) (II), 12, 1906. 



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