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.^ 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 



^ This will absorb the impurities in the oxygen. 



