REAGENTS. 23 



It is prepared by dissolving zinc in pure hydrochloric acid, and 

 evaporating the solution, on a water bath, in the presence of 

 metallic zinc until it has a syrupy consistence ; it is then saturated 

 with potassium iodide, and then with iodine ; a few grains of 

 iodine should be left in the liquid after it is poured off for use. 

 It may also be prepared by dissolving 25 parts of pure fused zinc 

 chloride and 8 parts of potassium iodide in 8^ parts of water, 

 filtering through asbestos, and saturating with Iodine. 



On adding Iodine to Schulze's solution till precipitation begins, 

 a fluid is obtained which stains the cell- walls yellow, and the 

 oallus of sieve-plates a deep brown (Russow.) 



Schulze's Macerating Fluid. 1 One gramme of 

 potassium chlorate is dissolved in 50 c.c. of nitric acid ; 

 the tissue is then placed in a small quantity of it, and 

 the whole is boiled for a short time in a test tube ; the 

 liquid is poured off, and the residue is well washed 

 with water. A filter may be used for washing. 



The cells become isolated in consequence of the 

 solution of the middle lamella. 



1 See Note, p. 22. 



