OSMOSIS 



Repeat these procedures with the other diaphragms until the condi- 

 tions and principles are fully understood. 



It is the cornea which causes usually the cylindricality of the refracting 

 media, and most often the defect is congenital although acquired, and 

 even changing, astigmatism is by no means rare, especially in children. 

 Oftentimes the curvature is irregular and beyond the correction of ground 

 lenses. 



All sorts of combinations of astigmatism with myopia or with hyperopia 

 are very common. 



XI. OSMOSIS. 



Expt. 102. (Apparatus: Dialyzer and the various solutions). (A) 

 Sodium Chloride. Half fill the inner tube of the dialyzer with the solu- 

 tion. Push the capillary tube downward until the solution rises half- 

 way up in it. Put the dialyzer in place. Note the direction of the 

 movement in the capillary indicator. Test with argentic nitrate for 

 sodium chloride. 



(B) Dextrose. Having carefully washed out at the sink the apparatus, 

 repeat the experiment with the dextrose-solution. Test the liquid in 

 the beaker for dextrose with Fehling's solution. 



(C) Glycogen. Repeat the experiment with the opalescent solution of 

 glycogen. Test the contents of the inner tube. 



(D) Potato-starch Solution. Repeat the experiment with the starch- 

 solution. Test the liquid in the beaker with iodine for starch. 



(E) Proteid. Repeat the experiment with egg-white solution. Test 

 the outer liquid for protein with Millon's reagent. 



34 



