On Sat, 02 Jan 2010 16:09:58 +0000, Dave Osborne
wrote:

Usenet Nutter wrote:
On Sat, 02 Jan 2010 14:32:48 +0000, Dave Osborne
wrote:

http://www.lpchemicals.com/product.p...ater+LR&Id=363

Thx for that ..Dunno what the "5 Water LR" means though .

"5 water" means 5 water of crystallisation aka pentahydrate

see: http://en.wikipedia.org/wiki/Sodium_thiosulphate

and http://en.wikipedia.org/wiki/Water_of_crystallisation

Anhydrous means "without water of crystallisation"

so 500g of anhydrous gives "more" hypo than 500g of pentahydrate,
because part of the amount you buy includes the weight of any water of
crystallisation.

===


LR means "Laboratory Reagent". Basically, you can buy chemicals in a
number of different grades.

"Crude" - with significant impurities. E.g Rock salt for putting on the
roads.

"Technical Grade" - pure enough for straightforward
industrial/commercial processes. May be contaminated with
inert/un-reactive substances. E.g. Swimming pool chemicals.

"Laboratory Grade" or "Laboratory Reagent" - containing very limited
amounts of impurities and sometimes guaranteed free of particularly
undesirable impurities (for some value of undesirable, which varies
according to context).

"Food grade" - suitable for human/animal consumption.

"Medical Grade" - which will have "BP" or "BPC" after. E.g. Sodium
Chloride B.P. This means that it has been manufactured/prepared and
tested/quality assured in accordance with the British Pharmacopoeia or
the British Pharmaceutical Codex.

"Analytical grade" or "analytical reagent" - extremely pure, for
chemical analysis and/or where any amount of insoluble impurity might
clog up the works of a sensitive scientific instrument.


HTH


Aah! Thanks for that ..Makes it totally clear ..If the use of this +
the previous use of HG Mould Remover works then that will be of use
to a few folk in here as the subject seems to come up regularly .