| 454 J 
XXXII. 
ON A SIMPLE AND ACCURATE METHOD FOR ESTIMATING 
THE DISSOLVED OXYGEN IN FRESH WATER, SEA 
WATER, SEWAGE EFFLUENTS, &c. By Prorsssor H. 
A GHEDS, DiSc:, Pa.D., Ano Ro HE. BAKE, EEC) ake Chos 
Queen’s College, Belfast. 
[COMMUNICATED BY DR. W. E. ADENEY, F.1.C., F.C.S. | 
[Read DecrmBer 19, 1900; Received for Publication January 28 ; 
Published Junz 11, 1901.] 
SeveRAL volumetric processes have been devised for determining 
the dissolved oxygen in fresh water, for which a considerable de- 
gree of accuracy has been claimed, and probably the best known 
are those of Schiitzenberger and Thresh. The first of these (origi- 
nally described in the Comptes Rendus, 75, p. 879, and in Schit- 
zenberger’s work on Fermentation) has received a considerable 
amount of attention from different observers,! and especially from 
Roscoe and Lunt,’ who introduced an important modification into 
the process, and compared the results obtained by the method thus 
modified with those yielded by boiling out the dissolved gases in 
vacuo, and determining the oxygen by gasometric analysis. In all 
the determinations, more oxygen appears to have been found by 
them by the volumetric than by the gasometric method. In 
London tap-waters, the greatest difference between the two sets of 
determinations amounted to 0°44 e.c. per litre, and the least to 
0-10, and they say :—‘‘The oxygen values obtained by the 
two methods show close agreement, considering the possible 
experimental error in so complex a comparison. The mean 
1 Kénig und Mentschler, Berichte 10 [1877], p. 2017: Konig, Berichte 13 [1880], 
p. 154: Tiemann und Preusse, Berichte 12 [1879], p. 1768; Bernthsen, Berichte 
13 [1880], p. 2277: Dupré, Analyst 10 [1885], p. 156: Ramsay and Williams, Chem. 
Soc. Journ. Trans. 49 [1886], p. 751. 
* Chem. Soc. Journ. Trans. 55 [1889], p. 552. 
