BLOOD GASES. 127 



When the analysis is completed, the mercury is run out from the 

 burette by the side tube (H), after removing the stopcock (C), 

 and the burette thoroughly washed with water. The mercury and 

 alkali pyrogallate solution (which is now brown in colour) are then 

 washed in running water until the washings react neutral to litmus 

 paper. The mercury should then be transferred to a separating 

 funnel containing a dilute solution of sulphuric acid. The blood 

 bulb should also be cleaned immediately, since otherwise a sticky 

 precipitate which is difficult to remove adheres to the walls. 



