560 Adeney — Dissolved Gases and Fermentative Changes. 



bottles, with the exception of one, were then carefully stoppered, and placed neck 

 downwards in distilled water. The one left unstoppered was at the same time 

 transferred to the gas analysis apparatus, and the volume of the liquid required 

 for the analysis then drawn from it into the burette of the apparatus, and thence 

 passed into the laboratory flask, and boiled in vacuo. 



Immediately this had been done, the preparation of the remaining dilutions 

 requii'ed is proceeded with in an exactly similar manner, except that portions of 

 them were not I'eserved for analysis. 



When all the dilutions have been made, five litres of tap-water were placed in 

 the same glass vessel, and agitated with air just as in the case of the dilutions. 

 The water after aeration is drawn ofP into bottles and preserved in the ordinary 

 way, a portion, as in the case of the lowest solution, being transferred to the gas 

 analysis apparatus. With the aid of an assistant, the analysis of the lowest 

 dilution and the prej^aration of all the required dilutions may be completed within 

 two hours, when the aeration, bottling, and analysis of the tap-water may be 

 pi'oceeded with without delay. 



The chief point of importance to be attended to in the preparation of these 

 dilutions is that of temperature ; it should be the same for each dilution. This is 

 not difficult to accomplish when the tap-water is drawn from so large a cistern as 

 that which has furnished my supply. I have also taken the precaution of tying 

 up the ball-cock of the cistern when making up the dilutions. 



The complete aeration of the dilutions is also of importance ; but, with a 

 good tap-water such as I have employed, this condition can be attained without 

 difficulty. 



In all my experiments I have endeavoui-ed to keep the variation of temperature 

 from that obtaining at their commencement within as narrow limits as possible, 

 and as a result of this I have found it unnecessary to make any correction for ex- 

 pansion or contraction of the liquid arising from change of temperature, the errors 

 arising therefrom being very small in comparison with those from other sources ; 

 thus the maximum difference between the initial and final temperature of any of 

 the experiments I shall quote in this Paper has been within 12" C, viz. from 

 8° C. to 19° C. A litre of water, on rising from 8°C. to 19° C, would increase 

 (according to the data given in Muir and Morley's edition of "Watt's Dictionary," 

 vol. iv., p. 861) in volume by 1*409 c.cs. Such an alteration in volume, it will be 

 seen from the details of my experiments, gave rise to so small an error in com- 

 parison with others which affected them that it was thought unnecessary to make 

 any correction for it. 



The errors arising from the tendency to disengagement of the dissolved gases 

 on variation of temperature would of course be very large, and in fact would 

 render the results valueless had not the precaution already described been taken 



