bv first running a Mream of water between the membrane and the 

 glas- wall. Prepare three membranes. 

 Prepare the following solution-: 



a. 50 cc. 2' , egg albnniin ]>lns 10 cc. distilled water. 



b. 50 cc. 2' , egg albumin ])lus 10 cc. m S XaL'l. 



c. 50 cc. _'' , egg albumin ])lus 10 cc. m S XaL'l.,. 

 In the outer vessel of each osinometer add respectively: 



a. distilled water. 



b. m 4* XaL'l. 



c. in 4S L'aL'L. 



t'se the same volume of outer fluid, e.g., 420 cc. in each osniometer. 

 I- ill each membrane with its corresponding solution : insert the rubber 

 cork and manometer tube into the neck of the membrane (excluding 

 air-bubbles) and bind in position \\-ith a rubber band. Then place 

 the membrane in position in its corresponding outer fluid and clamp 

 the manometer tube in a vertical position. 



Note the rise ot the fluid in the manometer tubes and the different 

 rates of rise. What is the maximum pressure in each solution: 

 \\hat do you conclude as to the influence of salts on the osmotic 

 pressure of colloids ? 



171. The prc-cnce of acid and alkali Increases the osmotic pres- 

 -ure of certain proteins, e. g.. gelatine. This action is prevented by 

 the presence of neutral salts in appropriate concentrations. Deter- 

 mine the osmotic pressure of the following solutions: 



a. I' ' f gelatine. 



b. \' e gelatine containing IU'1 to n 300 concentration. 



c. I', gelatine containing Xa<>ll or K<>ll [> 11/300 concentra- 

 tion. 



d. and e. Same as h and c but containing also XaC'l to m 4S 

 concentration. 



Keir.unber that the outer fluid contains the same electrolvtes 

 in the some concent ration as in the colloidal solution. 



< ompare the action of electrolytes on osmotic pressure with their 

 action on the s^'elliiit/ process. 



!:. EFFECT <>K SALTS ON COLLOIDS IX LIVING 

 TISSUES. 



S;nre the solid |>ortions (,f living tissue- are cnlliiids. it i- to be 

 expected that electrolytes \\j]l have a marked influence on vital 

 activities. The following experiments show the importance of 

 lvtcs for the aclivitv of ciliated cells. 



-14 



