Update from Alex Bruch, February 2013: Dr. Karty and I began this semester by studying both manganese sulfide and zinc sulfide Liesegang systems. After running a battery of experiments in attempt to obtain defined bands, we could not obtain a well-behaved reaction. I began to search literature for other candidates that may suit our study, such as mercury sulfide and cobalt sulfide. After careful consideration, Dr. Karty and I decided to begin researching a Liesegang reaction of copper sulfide in agar gel. We hope to have this reaction optimized with optical measurements before presenting my research at the National Conference on Undergraduate Research this coming April.