318 Prof. Adeney and Mr. Becker: Determination of Rate of 



comparative rapidity; and that this downward " streaming " 

 process, as Huefner * had termed it, must be regarded as of 

 great practical importance in such public health questions 

 as the protection of water-ways from the danger of fouling 

 by sewage matter; and in industrial processes, such as 

 brewing; and of such magnitude that the effects of ordinary 

 diffusion may, in comparison, be entirely neglected. 



A large number of additional experiments on this subject 

 has since been made by the same author, from time to time,, 

 during intervals of leisure from professional and official 

 work ; and the results have shown that the rate at which 

 water, when deprived of its usual air-content, dissolves and 

 absorbs the gases of the atmosphere, is a problem which 

 involves so many variable factors that its determination 

 experimentally is by no means so simple a matter as might 

 at first appear. Amongst the factors referred to are — the 

 humidity of the air and the initial air-content, salinity, tem- 

 perature, and depth of the water. Some of these factors 

 had, to some extent at least, already been studied f. But 

 before publishing the results obtained it w as thought desirable- 

 to make a careful experimental investigation of the question 

 oE the rate of solution of atmospheric gases by the exposed 

 surface-layer of a quiescent body of de-aerated water, apart 

 from that of the rate at which the gases " stream " downwards 

 through the lower layer of the water. 



It is proposed to describe in this communication the results 

 of a research which we have carried out with this object in 

 view. 



Experiments were in the first instance directed towards 

 carefully studying the influence of the thickness of a layer 

 of de-aerated water upon the rate at which it becomes 

 re-aerated, with a view to obtaining data by means of which 

 the factor of depth of water could be eliminated, when con- 

 sidering the question of the rate of solution by the surface- 

 layer of the water. 



With a view to obtaining a sufficiently extended series of 

 observations in any one experiment, under constant con- 

 ditions, or, in other words, within as short a time as possible, 

 it was intended to estimate the oxygen only in the water 

 under examination by a colorometric method. A number of 



* Ann. Phys. CJiem. (11), vol. ix. pp. 134-168 (1897). 



+ J. H. Coste has given a valuable notice and bibliography of the 

 published work on the Absorption of Atmospheric Gases by Water in 

 his two communications on the subject to the Journal of the Societv of 

 Chemical Industry, vol. xxxvi. p. 846, and vol. xxxvii. p. 170. 



