238 CHEMISTRY OF FARM PRACTICE 



thrown with great force on the fire. The chemical action 

 of the bicarbonate and acid is as follows : 



2NaHCO 3 + H 2 S0 4 = 2C0 2 + 2H 2 O + Na 2 SO 4 . 



To operate the extinguisher it is turned upside down and the 

 contents played on the fire by means of the hose attached 

 at the top of the cylinder when in operation. 



