Drs. Williamson «ra«? Russell on the Measurement of Gases. 527 



of the eudiometer, and by means of the fine adjustment bring the 

 column of mercury in the small tube exactly to the normal mark. 

 The eudiometer is then adjusted, also by .means of the slow move- 

 ment, so that the top of its meniscus (as seen through the horizontal 

 telescope) exactly coincides with the top of the meniscus in the 

 pressure-tube. This is easily done; for the diameter of the pressure- 

 tube is considerably smaller than that of the eudiometer, and the 

 meniscus in the latter can be clearly seen on both sides of the me- 

 niscus in the pressure-tube. 



By this method we are able to obtain very accurate results with 

 considerably less trouble than by Bunsen's method, and also without 

 having any calculations to perform. The following analyses made 

 during very stormy weather, of air deprived of its carbonic acid by 

 potash, gave results amongst which the greatest diflference was only 

 four-hundredths of a per cent. (•04). 



I. 

 Volume of air taken .... 144*81 

 After addition of hydrogen . . 234 •.50 

 After explosion 144 "00 



Nitrogen . , . 79-168 



Oxygen. . . . 20-832 



100-000 

 II. 

 Volume of air taken . . -. 139-55 



After addition of hydrogen '. . 229-07 



After explosion 141-89 



Nitrogen . . . 79-176 

 Oxygen. . . . 20-824 



100-000 

 III. 

 Volume of air taken . . . . 148-1 

 After addition of hydrogen . . 236-04 



After explosion 143-30 



Nitrogen , . . 79-139 

 Oxygen. . . . 20861 



100-000 

 IV. 

 Volume of air taken .... 149-14 

 After addition of hydrogen . . 248-.57 



After explosion 1.5.5-28 



Nitrogen . . . 79-1.50 

 Oxygen. . . . 20-8.50 



Too^ooo 



We are still engaged in experiments on this and some other points 



