1892.] Relative Densities of Hydrogen and Oxygen. 



Hydrogen. 



457 



Oxygen. 



In almost every case the weight of the globe full is compared with 

 the mean of the immediately preceding and following weights empty. 

 The numbers recorded in the second column are derived from the 

 readings of the balance by the introduction of corrections 



(1.) For the errors of the weights themselves, found by a sys- 

 tematic comparison, only relative values unconnected for buoyancy 

 being required. 



(2.) For the deviation of the mean* barometric reading at the time 

 of filling from 30 inphes (as read upon the vernier). 



(3.) For the deviation of the temperature of the barometers 

 (Column 3) from 6l> F. 



(4.) For the deviation of the temperature of the gas (as read upon 

 the thermometers) from 12 C. 



As an example, I will take in detail the calculation for the hydro- 

 gen filling of October 26. After the evacuation of October 24, the 

 working globe (14) with its compensating volume piece and 



* There were two barometers. 



2 i 2 



