68 W. H. E M I G 



After standing for three or four days exposed to the air and light, 

 the solution is filtered and 100 cc each of glycerin and methyl alcohol 

 are added. The solution is now allowed to stand until the color is 

 sufficiently dark and is then filtered and kept in a tightly stoppered 

 bottle. This solution must be considerably diluted with water be- 

 fore using." (N. Y., April 18th, 1885.) 



This original formula of Delafield (as given above) contains a 

 number of errors. It is impossible to dissolve four grams of 

 Haematoxylin in 25 ml. of strong alcohol because the solubility of 

 the dye is approximately £ per cent. Therefore, if only the dis- 

 solved portion of the dye is added to the alum solution, about 95 per 

 cent of the crystals remain unused. Since Haematoxylin is slightly 

 more soluble in ammonium alum than in alcohol, it is unnecessary 

 to use alcohol as a solvent. As soon as alcohol is added to aqueous 

 ammonium alum, the few crystals first thrown out of solution serve 

 as centers for the rapid growth of larger crystals. Ammonium 

 alum is soluble in water but insoluble in alcohol. At the time the 

 stain is filtered, a considerable quantity of the dye and half of the 

 alum remain undissolved. Since it has long been the practice of 

 technicians to employ concentrated stains, a saturated solution of 

 Haematoxylin in ammonium alum, then, is evidently what Delafield 

 wished to obtain. 



Taking into consideration the characteristic properties of 

 Haematoxylin as a dye, a saturated stain containing ammonium 

 alum is made in accordance with the formula given below. 



Alum Haematoxylin (aluminum Haematoxylin). 



Distilled water .... 160 ml., the solvent 



Alcohol, 95% 40 ml., the preservative 



Ammonium alum . . 10 grams, the mordant 



Haematoxylin 1 gram, optimum solubility 



This staining solution is ripened in three days if kept at 60° C. in a 

 liter Erlenmeyer flask plugged with cotton. After having been 

 ripened, the stain is filtered. By adding 20 ml. of glycerin, which 

 retards the oxidation of the stain, the keeping qualities are im- 

 proved. Should methyl alcohol instead of ethyl alcohol be added 



