Testing for Iron 233 



basic aniline dyes such as fuchsin. They are metac liromatic (page 110) 

 with methyl green and give a positive Schiff reaction after periodic 

 acid treatment (page 298). Reference: Ham (1957). 



Testino^ for Iron 



According to Baker (1938) the iron reaction is an example of local 

 formation of a colored substance which is not a dye. It is a type of histo- 

 chemical test wherein a tissue is soaked in a colorless substance. Certain 

 tissue elements react with the substance and become colored. The '^veil- 

 known test is the Berlin blue, Prussian blue or Perl's reaction, in which 

 the iron is dissolved from hemosiderin by hydrochloric acid, and then 

 reacts with potassium ferrocyanide to form the Berlin blue precipitate, 

 ferric ferrocyanide. 



Sometimes fading occurs in slides due to the reduction of the Berlin 

 blue to colorless ferro ferrocyanide. The mounting resin probably takes 

 up oxygen while drying and deprives the sections of oxygen, thereby 

 reducing them to the colorless condition. If this takes place and it is 

 essential to recover the slides, treat them with hydrogen peroxide. The 

 newer synthetics are not as prone to reduce Berlin blue as former resins; 

 also Lustron 2020 is recommended (page 118). 



Iron Reaction (gomori, 1936) 



fixation: 10% buffered formalin; other general fixatives are satis- 

 factory but acid content may dissolve some of the hemosiderin (iron 

 bearing pigment, Lillie, 19')4B). 



solutions: 



Hydrochloric acid, 20%: 



hydrochloric acid (sp.gi-. 1.188-1.192, 37-38% 



HCI) 20.0 ml. 



distilled water 80.0 ml. 



Potassium ferrocyanide, 10%: 



potassium ferrocyanide, K4Fe(CN)c-3H20 .... 10.0 gm. 

 distilled water 100.0 ml. 



Safranin: 



safranin O, C.I. 50240 0.2 gm. 



distilled water 100.0 ml. 



glacial acetic acid 1.0 ml. 



