18 



EXPERIMENTAL PHYSIOLOGY 



VIII. PROPERTIES OF OXYGEN. 



Apparatus. Chlorate of potash (potassium chlorate), manganese 

 dioxide, piece of phosphorus, stick of charcoal, sulphur, fine iron wire, 

 Florence flask, one-holed rubber stopper, rubber and glass connect- 

 ing tubing, wash bottle fitted with two-holed stopper, ring stand, 

 sand bath, pneumatic trough, five large-mouthed glass bottles with 

 glass plates to cover, caustic soda, Bunsen burner or alcohol lamp, 

 deflagrating spoon. 



Directions. Set up the apparatus as in Fig. 5. Place 



FIG. 5. 



in the flask to a depth of half an inch a mixture of one part 

 of manganese dioxide to four parts of chlorate of potash. 

 Fill the wash bottle about half full of water and dissolve 

 a stick of caustic soda in it. 1 When everything is connected 

 as in the diagram heat the flask gently on the sand bath. 

 The first of the gas produced will mix with the air in the 



1 This will absorb the impurities in the oxygen. 



