From: DonRath@aol.com
Date: Sat Dec 01 2001 - 11:02:10 PST
From: DonRath@aol.com Message-ID: <9d.1f356ef3.293a8332@aol.com> Date: Sat, 1 Dec 2001 14:02:10 EST Subject: Crystal Lab
Pam --
Here are some solutions you can use for the lab you described: ammonium
chloride (gives absolutely beautiful, tree-like, dendritic crystal patterns);
potassium permanganate (long, distinctive, needle-like crystals -- but the
solution is messy to handle since it stains); sodium chloride (common table
salt -- gives cubic crystals); common alum (potassium aluminum sulfate -- you
used to be able to buy this in a drug store, but I haven't tried for a long
time); copper sulfate. We used to put a small puddle of a saturated solution
on a microscope slide, and hold the slide over a light bulb until a crust
started to form around the edge of the puddle -- then look at the slide under
a microscope (normal with low power, or a binocular dissecting scope). You
can watch the crystals grow! The ammonium chloride is a knockout! Two other
chemicals that we used were salol and thymol -- but they have a somewhat
nasty odor, and perhaps should be used under a hood -- you might check the
toxicity! -- for these chemicals you put a small amount of solid on the
microscope slide and then let the solid melt over the light bulb -- when it's
melted, take the slide away from the light bulb --when it starts to
recrystallize, immediately look at it under the scope -- the growth is rapid.
Hope this helps.
Don Rathjen
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