AND RATIO OF THEIR ATOMIC WEIGHTS. 



19 



which is connected to the globe. The ground joint of the globe was placed in n, 

 and made tight with melted wax or paraffin. The globe, tube, and stopper were 

 put in place, and the tube o was connected by fusion to the tube g h leading 

 to the air-pump, the mano-barometer, and tlie generator of oxygen. The stop- 



& 



Fu;. 6.— Calorimeter case for measuring temperature uf oxygen. 



cock c l)eing open, the whole connected appai'atus was exhausted, and the 

 degree of exhaustion measured. The stopcock of the globe, h, could now be 

 opened, and the degree of its exhaustion verified, if re(piired, as, for instance, if the 

 globe had jnst been weighed while exhausted, and it was desii'ed to know if 

 leakage had occurred. The globe was then closed during the further pi'eparation 

 of the apparatus for producing pure oxygen. 



14. PRKPARA'riON OK OXYGEN. 



In ail the experiments of tliis series, oxygen was obtained from potassium 

 chlorate. A tube of infusible glass, a a, Fig. 7, was filled with the required (quan- 

 tity of the salt, the end a d was diaw ii out and fused to a ground joint made of the 



