Have you ever seen the Silver Mirror trick at a chemistry show?  That’s when silver is precipitated out of solution onto a glass surface.  The demo consists of a series of clear solutions being combined in a glass flask.  As the presenter swirls the flask, a shiny mirror forms on the inner surface of the glass.  The reaction utilizes Tollens’ reagent, which is used to determine the difference between aldehydes and ketones.  I thought it might be cool to modify the procedure slightly to be able to grow silver crystals.  This turned out to be slightly more challenging than I predicted, mostly because the Tollen’s reagent is designed to form a smooth silver film on any glass surface, so crystals are not the first structures produced.  However, with some tweaking and dilution, I was able to get a slide with some individual crystals.  Above is a picture through the Foldscope and below is a macro photo of the prepared slide.