Hutchinson — On the Estimation of Oxygen in Water. 135 



XXII. — On Schtjtzenbeegee's Peocess foe the Voitjmeteic Estima- 

 Tioisr OF Oxygen in Watee. By Cheistophee Claeke Hutchinson, 

 Eoyal Exhibitioner, Eoyal College of Science. 



[Read, December 10, 1877.] 



In judging of the character of a water for domestic uses, one of the 

 most important points to be ascertained is, the question of its pollu- 

 tion by sewage and other deleterious matters. 



The determination of this pollution, its extent and nature, is 'at 

 present rather unsettled. It is, however, believed by many chemists 

 that a contamination, such as referred to, will exercise an effect upon 

 the gaseous bodies held in solution in a water. It is the opinion of 

 many, that the relative quantity of oxygen present in a water affords 

 the key to its deterioration by organic matter ; because it is unlikely 

 that a large quantity of oxygen can be held in solution by a water 

 containing oxidizable matter. "Waters which contain their normal 

 proportion of oxygen, in relation to their other gaseous constituents, 

 Avould be regarded as free from sewage and decaying matter ; a dimi- 

 nution in the quantity of oxygen would indicate a corresponding 

 increase in the amount of injurious matter present. 



The late Dr. Miller's analyses of the gases present in the water of 

 the Thames, at various points, clearly proved that as the amount of 

 sewage increased, the amount of carbonic acid increased, and the 

 amount of oxygen decreased. 



The Elvers' Pollution Commissioners state in their sixth Eeport 

 that the proportion of oxygen in water is deprived of much import- 

 ance, since it has been discovered that deep well waters, which cannot 

 contain putrescent organic matter, contain little or no dissolved oxygen. 

 The absence of oxygen in deep well waters may, however, be owing 

 to its having oxidized and destroyed the organic matter the water pre- 

 viously contained, during its percolation through the strata. 



In the presence of this conflicting testimony, I was induced to 

 undertake an investigation, in the hope of throwing some light upon 

 this important question — whether or not the amount of oxygen pre- 

 sent is, or is not, an indication of the freedom of a water from injurious 

 organic bodies. 



In commencing the inquiry I was desirous of employing some 

 accurate, and yet rapid, method, for the estimation of the oxygen 

 present ; for although the gasometric operations by Bunsen's method 

 leave nothing to be desired in point of accuracy, yet on account 

 of their somewhat tedious nature some other plan, if even slightly less 

 accurate, but at the same time more rapid, would be desirable. 



Such a method as this I thought might be afforded by the process 

 devised by Schutzenberger for the volumetric estimation of oxygen in 



K. I. a. PEOC, SEK. II., VOL. III. — SCIENCE. L 



