142 



Lord Rayleigh. 



[Mar. 23, 



filled with fragments of potash, and a long length of phosphoric 

 anhydride, followed by a filter of glass wool. The arrangements 

 beyond the regulating tap were the same for all the gases experi- 

 mented upon. At the close of the filling it was necessary to use a 

 condensing syringe in order to force the pressure up to the required 

 point, but the air thus introduced would not reach the globe. It 

 may be well to give the results for air in some detail, so as to enable 

 the reader to form a judgment as to the degree of accuracy attained 

 in the manipulations. 



Date. 



G-lobe 

 empty. 



Globe 

 full. 



Temp, of 

 manometer. 



Correction 

 to 15°. 



Corrected 

 to 15°. 



1892. 













Sept. 24 



2 -90941 











„ 27 .... 





0-53327 



17 -8 



-0-00112 



0-53219 



„ 28 .... 



2 -90867 











„ 29 .... 





0-53271 



15 -7 



-0-00028 



-53243 



Oct. 1 



2 -90923 











» 3.... 





-53151 



12 -7 



+ 0-00093 



-53244 



„ 4.... 



2 -90872 















Tap regreased. 







„ 7.... 



2 -91036 











„ 8.... 





-53296 



12 -4 



+ 0-00105 



0-53401 



„ 10.... 



2-91056 











„ 11 .... 





0-53251 



11 -8 



+ -00129 



0-53380 



„ 12 ... . 



2-91039 











„ 13.... 





0-53201 



11 -o 



+ 0-00161 



0-53362 



„ 14.... 



2 -91043 











„ 15 .. .. 





-53219 



10-6 



+ 00177 



53396 



The column headed " globe empty " gives the (corrected) weights, 

 on the side of the working globe, required for balance. The third 

 column gives the corresponding weights when the globe was full of 

 air, having been charged at 0° and up to the pressure required to 

 bring the mercury in the manometer into contact with the two points 

 of the measuring rod. 



This pressure was not quite the same on different occasions, being 

 subject to a temperature correction for the density of mercury and 

 for the expansion of the iron rod. The correction is given in the fifth 

 column, and the weights that would have been required, had the 

 temperature been 15°, in the sixth. The numbers in the second and 

 sixth columns should agree, but they are liable to a discontinuity 

 when the tap is regreased. 



In deducing the weight of the gas we compare each weighing 

 " full " with the mean of the preceding and following weights 



