IXTRODUCTIOX. $ 



Alcohol, Magenta, 



Potassic hydrate, Glycerine, 



Iodine, Sulphuric acid, 



Chlor-iodide of zinc. Potassic chlorate solution. 



The alcohol used is the commercial article, 95 per 

 cent. pure. 



The potassic hydrate is a 5 per cent, solution of 

 potassic hydrate in distilled water. Sodic hydrate will 

 answer the same purpose. The " liquor potassae " of 

 the U. S. Dispensatory is of this strength and may be 

 purchased of any druggist. 



The iodine is prepared as follows : Dissolve 3 gm. of 

 iodide of potassium in 350 cc. of distilled water ; add I 

 gm. of sublimed iodine. A weaker solution will be 

 useful, viz., potassic iodide 3 gm., distilled water 500 

 cc., iodine I gm. The tincture of iodine diluted till it 

 is a sherry brown color will answer in some cases, but 

 is not so generally useful as the solution recom- 

 mended. 



Chlor-iodide of zinc may be prepared as follows: Dis- 

 solve metallic zinc in concentrated hydrochloric acid 

 until the action ceases ; evaporate to the consist- 

 ency of syrup in contact with metallic zinc ; saturate 

 this with potassic iodide ; add as much iodine as it will 

 take up, with some excess. 3 It is better to keep the 

 solution in a dark place, although in the majority of 

 instances the proper reaction will be secured without 

 this precaution. 



Magenta is a solution of the aniline color of that 

 name. It may be purchased of dealers in microscopi- 

 cal supplies or made as follows : Powder I gm. crystal- 

 3 Poulsen and Trelease, Bot. Micro-Chemistry, p. 8. 



