The experiments on which these notes were made were undertaken to clear up a little of the mystery which has been thrown around the subject by well-meaning but not always chemically-minded people. Much has been said lately on the necessity for prehistorians being also geologists, but it is perhaps too much to ask that they shall, in addition, be chemists. But a very little knowledge of chemistry would have averted some of the blunders and misstatements met with on the patination problem. These notes contain no really original idea, but were made on experiments proving what to most chemists are well-known facts. The experiments were carried out in the brief intervals of routine work in a very busy laboratory, unfitted with any special re-agents or apparatus for the work.

Silica is, chemically speaking, the dioxide of the element silicon, a body which does not appear to exist in a free state in nature, and which can only be brought into a free or elementary state by some what tedious laboratory processes.