250 



Ellinor Archer : 



In order to prove that the solution of lead nitrate did actually 

 prevent blocking in the vessels, and allowed a freer passage through 

 the stems the following experiment was performed. 



Two short stems of as nearly as possible the same length and 

 ■diameter were fixed in a perpendicular position. To the upper 

 end of each was attached a small rubber tul>e connected with a small 

 reservoir, while to the lower end a small graduated flask was also 

 connected by a rubber tube. 



Reservoir A, attached to Stem A, was filled witli water, and 

 Ue.servoir B, attached to Stem B, was filled witl) a 1% solution of 



