26 OSMOTIC PRESSURE OF AQUEOUS SOLUTIONS. 



Still another glass device for attaching the manometer to the cell is 

 seen in Figure 14. It was designed for use with the form of cell which 

 is seen in Figure 11. The manometer (a) passes entirely through the 

 closed tube (b), whose outside diameter is only a little less than the 

 interior diameter of the cell. The means for compressing the packing 

 (c, d, e, f, and g) and fixing the large tube (b) in the cell do not differ 

 essentially from the analogous parts seen in Figure 11, except that the 

 lower ring (e) is made of porcelain, in order that the solution in the 

 cell may nowhere come in contact with metal. The adjustment of 

 pressure within the cell is effected by means of the brass pieces (h, 

 which is fixed in its place with cement) , (i), and (J). The vent (k) is not 

 absolutely necessary, though it is sometimes a convenience. Instead 

 of opening the vent when it is desired to lessen the pressure, the nut 

 (j) may be turned slightly to the left. 



The device shown in Figure 15 is a substitute for that seen in Figure 

 14. The two differ only in that the large tube (b) is closed at both 

 ends in Figure 14, while it is open at the top in Figure 15. The latter 

 is easier to make, and is in no way inferior to the closed form. 



