Our/ Your New range of Bell Jars.
These are pretty much like the ones y would imagine, except they have a joint at the top.
This makes adding a vacuum possible, via a flow controll adapter, or a jointed stopcock.
THe bottom surface is ground, to provide a flat surface.
Watch Glasses are generally used for drying crstals and samples.
They provide a see through, clean concave base, for liquids to gravitate towards the centre, whilst crystallising.
THey have lots of other uses, pefhapds,burning ants, but scientifically speaking, are pretty much the standard in crystal forming.