Tin Crystals from Tin(II) Chloride
Electrolyzing tin(II) chloride (stannous chloride) into crystals of pure tin. I've seen this done before, but I've never seen it under a microscope.
I used 4ml of 31.45% hydrochloric acid in 40ml of distilled water. I then dissolve about 9g of tin(II) chloride (excess is ok). I used an 11V 1A DC power supply. The crystals grow from the negative electrode. Turn on the power supply, let a few small crystals grow, lift the electrode to expose the crystals to air, then dip it back into the solution. To dispose of the solution, add baking soda or sodium hydroxide until it has a neutral pH (test with universal indicator). It is then safe to dump (check your local regulations).
The microscope was at 100x magnification (10/0.25:160/0.17 objective, 10x eyepiece). Instead of using the backlight, I used two lamps on either side illuminating it from above. Yes, I know my microscope is a cheap piece of junk!