232 



ESSENTIALS OF CHEMICAL PHYSIOLOGY 



blood is brought into it by the tube c ; the gases, as they come off, cause the 

 blood to froth, and the bulb, 6, is called the froth-chamber, as it intercepts 

 the froth, preventing it from passing into the rest of the apparatus. 



The pump is used in the following way : I is filled with mercury, the 

 level in I and o being the same ; k is closed ; o is then lowered, and when it 



FIG. 79. Diagram of PflUger's pump. 



is 30 inches lower than the stopcock, &, the mercury in I falls also, leaving 

 that bulb empty : .;' being closed and / open, ~k is then opened, and the air in 

 a, b, d, &c., rushes into the Torricellian vacuum in I ; / is closed and j opened ; 

 the reservoir, o, is raised ; the mercury in I rises also, pushing the air before 

 it, and it bubbles out into the atmosphere through the mercury (the tube, 7i, 

 is not at this stage in position). When I is full of mercury, k andj are once 



