72 Royal Society : — Mr. O. Reynolds on the Condensation 



Table II. shows the result of au experiment after the second 

 method, in which the pressure within the flask remained constant, 

 whilst the flame and condensation were reduced as the air was ad- 

 mitted. In this experiment the rate at which the water passed 

 through the condenser was constant from first to last, and conse- 

 quently the temperature of the effluent water varied with the con- 

 densation. 



Table III. shows the result of an experiment, also made accord- 

 ing to the second method, but in which the quantity of water 

 flowing through the condenser was so varied that the temperature 

 of the effluent water remained constant. 



13. Each of these Tables shows the effect of air on the condensa- 

 tion in a very definite manner; but the results as given in the 



Drons 

 column p in Table I. cannot be compared with the — - in Tables 



II. and III. as they stand ; for these show the effect of the air in a 

 series of increasing figures. If, however, these figures show the 

 power of the air to diminish condensation, then they will be in- 

 versely proportional to the quantity of water condensed, i. e. what 

 would have been condensed if the pressure and other things had 



remained constant. Hence the numbers in the column — should 



**' 



Drops 

 be proportional to the numbers in the column — in Tables II. 



and III. 



In order to compare the results of these experiments, the results 

 in each Table have been multiplied by a common factor, so that 

 they may be the same when the pressure of air is one tenth that of 



the steam. Thus the numbers in the column — in Table I. have 



Drons 

 been multiplied by 2000, and numbers under - — — in Table II. by 7. 



The result of the experiments thus reduced are shown in the curves 

 1, 2, 3. 



The point of no air might have been chosen as the point in w T hich 

 the curves should coincide ; but, as has been previously explained, 

 the results under such circumstances are to be taken as indicating 

 the power of the condenser to carry off the heat. Had it been 

 possible to keep the condenser cool, then there is reason to believe 

 that there would have been no limit to the condensation of pure 

 steam, and that the true form of the curves is like that shown by 

 the dots. 



Although the curves do not coincide, yet they are all of the same 

 form, and the difference between them is not greater than can be 

 accounted for by the disturbing causes already mentioned. They 

 all show that the effect of air begins to fall off rapidly when its 

 pressure amounts to one tenth that of the steam, and that when 

 it amounts to about one fourth that of the steam the admission of 

 more air produces scarcely any effect. 



