Dealing with a single case of metachromatic leukodystrophy - a sural nerve 
biopsy specimen - about thirty years ago - I found the literature about the 
"brown metachromasia" of the cerebroside sulfatide storage product (in this 
dismal inherited disease) to be extremely unsatisfactory - and I can read 
German.

A simple toluidine blue stain sufficed to demonstrate it, as I remember, but 
mounting was a problem. Going directly through water to dioxane, with a 
homemade mounting medium of polystyrene dissolved in dioxane, was what we did 
at the time. (Dioxane has a reputation for toxicity that probably precludes 
its use today.)

The brown metachromasia lasted for about a day. I believe that the only 
permanent medium for brown metachromasia is photographic film!

Bob Richmond
Samurai Pathologist
Knoxville TN