170 



Fig. 2 shows the apparatus in a position on the ring stanci A loi 

 filling the pipette E. If one opens C the NaOH solution in D will run 

 into G which, when I is open, will cause the bar>i;a solution to rise in 



r<^ 



if- 



E to the desired height. If now C and I are closed and B opened it 

 will allow the air to enter D when .J is opened and the solution allowed 

 to run out. The NaOH or KOH solution in D will arrest any COi: pres- 

 ent so that the baryta solution will remain clear. The baryta solution 

 in L remains clear since the calcium chloride tube K, which contains 



