Becker — Apparatus for Observing Reaction between Gases, etc. 343 



VI. — COMPAKISON OF EeSULTS. 



The results obtained in Experiment 6 are shown as a graph in fig. 8 in 

 order to afford a comparison between the rate at which the oxygen is absorbed 

 by quiescent water and the rate when the water is stirred. The water was at 

 first stirred for two minutes in order to mix the ferrous hydrate with the 

 liquid, and thus reduce the oxygen content to zero. During this period the 

 rate of absorption was of the same order as obtained in the other experiments. 

 The stirring was then stopped, and the rate fell off slowly as the liquid came 

 to rest until it reached a value which remained nearly constant for three 

 days. On the third day this suddenly changed for a higher value, which 

 remained constant until the sixth day, by which time only about half the 

 saturation value had been reached. The liquid was then stirred again, and the 

 remainder of the absorption was completed in about five hours. Hence a 

 process of absorption which may take many days to complete when the water 

 is quiescent takes place in as many hours with moderate stirring. 



Time in Days. 

 Fig. 8. 



The sudden change in the rate of solution of oxygen by the quiescent 

 water indicated above is characteristic of the process under these conditions, 

 for the rate of solution of gases by water is then liable to sudden and 

 unaccountable variations within narrow limits. 



The greatest value for the rate of solution per unit area given in the table 

 represents the maximum rate attainable under the conditions of these 



