Mayer’s hemalum
50 g aluminum potassium sulfate (KAl[SO4]2•12H2O)
1.0 g hematoxylin (C.I. 75290)
1.0 g citric acid (monohydrate)
H2O (to 1000 mL)
Dissolve the above reagents in the order given in 750 mL of H2O. A magnetic stirrer will hasten dissolving of the alum, hematoxylin, and hematein formed by iodate oxidation. To prolong the working lifetime of the stain, this solution is made with only half the quantity of sodium iodate stipulated in Langeron’s formulation. Mayer’s hemalum often keeps for 1 yr but some batches lose their potency after only a few months. The solution may be reused many times. Some authorities recommend boiling the solution and filtering when it has cooled, but boiling does not seem to be necessary. The function of the chloral hydrate is questionable; some workers simply omit it, and some make up to 1 L with 250-300 mL of glycerol or ethylene glycol.
