Chlorazol Black E in Aqueous Alkaline Solution

Chlorazol black E has a greater solubility in alkaline than in neutral aqueous solution. A method of preparing an alkaline solution (a 1% aqueous solution, heated 5 minutes at 70° C. with 0.2% concentrated ammonia water) for general tissue staining is described, together with notes on its use. The solution was unsatisfactory as a negative stain for bacteria.