Formulae for Reagents 301 



alum in a liter of distilled water. Allow the mixture to cool and 

 settle; filter; add a crystal of thymol to preserve from mold (Lee). 



It is ready for use as soon as made up. Unless attacked by mold, 

 it keeps indefinitely. 



Haidenhain's Iron-Haematoxylin.--This stain was introduced 

 by Haidenhain in 1892 and has gained a well-deserved popularity 

 with those engaged in cytological work. Two solutions are used, 

 and they are never mixed: 



A. 1| to 4 per cent aqueous solution of ammonia sulphate of iron. Use 

 the ferric (violet) crystals, not the ferrous (green) crystals. 



B. | per cent solution of haematoxylin in distilled water. 



The crystals of haematoxylin will dissolve in the distilled water 

 in about 10 days; the stain reaches its greatest efficiency in about 

 6 weeks. About 3 months from the time it is made up, it begins to 

 deteriorate. A stain made by dissolving the crystals in strong alco- 

 hol and then diluting with water so as to get a practically aqueous 

 solution is not so good. 



Greenacher's Borax Carmine.- 



Carmine 3 g. 



Borax 4 g. 



Distilled water 100 c.c. 



Dissolve the borax in water and add the carmine, which is quickly 

 dissolved with the aid of gentle heat. Add 100 c.c. of 70 per cent 

 alcohol and filter (Stirling). 



Alum Carmine. A 4 per cent aqueous solution of ammonia alum 

 is boiled 20 minutes with 1 per cent of powdered carmine. Filter 

 after it cools (Lee). 



Alum Cochineal.- 



Powdered cochineal 50 g. 



Alum 5 g. 



Distilled water 500 c.c. 



Dissolve the alum in water, add the cochineal, and boil; evaporate 

 down to two-thirds of the original volume and filter. Add a few 

 drops of carbolic acid to prevent mold (Stirling). 



