382 APPENDIX 



8. Chlor-iodide of Zinc [Schuhe's Solution). 



Use. — A delicate test for cellulose; turns cellulose cell- 

 walls and starcli grains blue, protoplasm trown, and 

 corky and lignified cell-walls brown. 



Preparation. — To strong hydrochloric acid add some pure 

 zinc until no more will dissolve. Set the solution in a 

 warm place, add more zinc, and evaporate the fluid un- 

 til it has a syrupy consistency. To the solution add 

 crystals of potassium iodide until no more will dissolve, 

 then saturate the mixture with metallic iodine. This 

 gives a dark -brown, concentrated solution, which may 

 be diluted until it has the color of sherry-wine by add- 

 ing the requisite amount of a solution of one part of 

 potassium iodide dissolved in twenty parts of water. 

 Keep the solutions in a dark place. 



9. Chromic Acid. 



Use. — A one-half per cent, solution may be used for hard- 

 ening tissues ; strong aqueous solutions dissolve lignified 

 and cellulose cell-walls. 



Preparation. — Chromic acid comes in the form of red crys- 

 tals. Make a four per cent, solution by dissolving four 

 grams of the crystals in ninety-six cubic centimetres of 

 distilled water. Dilute this solution as required. Keep 

 the solutions of chromic acid in the dark. 



10. Copper Sulphate. 



Use. — Used with sodium hydrate as a test for glucose and 



for albuminous (proteid) substances. 

 Preparation. — Dissolve one gram of the crystals of copper 



sulphate in ninety-nine cubic centimetres of distilled water. 



11. Corrosive Sublimate. 



Use. — Is a hardening agent, and kills small animals almost 

 instantaneously. Do not handle with steel instruments 

 specimens killed in corrosive sublimate. 



Preparation. — Saturate distilled water with mercuric chlo- 



