From: Judy Seigel (jseigel@panix.com)
Date: 03/20/02-03:06:51 PM Z
On Wed, 20 Mar 2002, alnovo@inwind.it wrote:
>
> Those "watch glasses" are used because one can wash them while
> transferring the chemical to the vessel, to be sure that truly *all* the
> weighted substance goes into the solution. This is particularly needed
> for an exact weighting, such as for very small amounts.
You mean WASH glasses? You sluice the chemical off with water?.. that
sounds, um ... messy? & what if you only want a little water? Or alcohol?
Of course the difficulty in getting the chemical off that round surface,
especially into something narrower than it is (I often transfer into a
graduate, for instance), would more than cancel out any supposed
advantage. Transfer from round without a spout shape is another accident
waiting to happen.
I agree otherwise, except about the kitchen aluminum foil -- too likely to
crinkle & hold powder...
Judy
> I don't like plastic, as very often it is electrized and the powder to
> be weighted spreads all over the surface and sometimes also out and
> under the plastic vessel. It is better -in a domestic environment- an
> aluminium foil, tissue paper, typing paper or baking paper depending on
> the nature of the substance. Do not use aluminium or paper for sodium
> or potassium hydrate, other caustic or higly acidic substances: in these
> cases plastic and glass are a must.
>
> Alberto
>
> http://spazioweb.inwind.it/albertonovo/index_eng.html
> http://www.grupponamias.com/novo/index_en.htm
>
>
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