236 Pigments and Minerals (chap. 17) 



3. Treat with yellow ammonium sulfide: 1-3 hotirs. 



4. Rinse in distilled water. 



5. Treat ^vith equal parts of potassitim ferricyanide and hydrochloric 

 acid, freshly mixed: 10-20 minutes. 



6. Rinse in distilled water. 



7. Counterstain with safranin (or other red nuclear stain): 2-3 

 minutes. 



8. Rinse in 707o alcohol. 



9. Dehydrate, clear, and moinit. 



results: 



ferrous iron and ferric iron converted to ferrous iron — deep blue 

 other tissue elements — shades of rose and red 



Iron Reaction: Di-nitrosoresorcinol (Humphrey, 1935) 

 fixation: 10% buffered formalin, general fixative without acid. 



solutions: 



Ammonium stilfide, 30% analytical reagent. 



Di-nitrosoresorcinol (resorcin green), saturated aqueous solution, or 



a 3% solution in 50% alcohol. 



procedure: 



1. Deparaffinize and hydrate slides down to water. 



2. Treat with ammonium sulfide: 1 mintue. 



3. Rinse in ^vater. 



4. Transfer to di-nitrosoresorcinol: 6-24 hours. 



5. Wash in water (or 50% alcohol). 



6. Dehydrate, clear, and mount. 



results: 



iron — dark green 

 background — brown 



comments: 



Reagent is more effective if solution has aged for a few days. Undis- 

 solved chemical should be present in the saturated aqueous solution. 

 Author's reaction — a disappointingly dull slide. 



Testing for Calcium 



Von Kossa, modified from Mallory (1944) 



fixation: 10% formalin or alcohol, although other fixatives give reason- 

 ably good results. 



