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From: bz on 10 Mar 2010 13:58
"N_Cook" <diverse(a)tcp.co.uk> wrote in
news:hn50n6$ni2$1(a)news.eternal-september.org:

> Arfa Daily <arfa.daily(a)ntlworld.com> wrote in message
> news:Zwfln.241303$Np2.139437(a)newsfe24.ams2...
>>
>> "N_Cook" <diverse(a)tcp.co.uk> wrote in message
>> news:hn2lj4$ond$1(a)news.eternal-september.org...
>> >A chemist gave me enough potassium chromate to have a go. Ground off a
....
> That was what I was thinking. And it wold take more than acid rain to
> leech the lead from solder, or lead would not be possible to be used as
> the plates in car batteries.
> The only "lead" test pens I've seen are in paints section of hardware
> and at 8 GBP a pop and nothing on the package about being used on more
> than one occassion, they can stay on the shelves. Those would be for red
> lead in paints, which is not elemental lead, so probably would not work
> either
>
>

The lead must be in solution to be detected with potassium chromate.

The procedure in my qualatative analysis text book for alloys starts with
disolving a small sample in hot nitric acid.

The reaction with the chromate ion requires that the lead be in solution in
the form of the Pb++ ion.

The test depends on the formation of a yellow insoluble lead chromate.

The test will not work unless the lead is in solution and the pH of the
solution is correct.

There ARE tests that will detect lead without putting it into solution, X-
ray fluorescence for example.

--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.
From: Michael A. Terrell on 10 Mar 2010 15:50

Arfa Daily wrote:
>
> Or of course as lead flashing on every house ever built, or lead guttering,
> as is found on many old - and even ancient - buildings, and has been there
> for hundreds of years, being 'dissolved away' (ha!) by the rain for all that
> time, including the several decades of bad-arsed acid rain, that we had in
> the last century ...


Some US homes have a sacrificial strip of Zinc along the ridges on
roofs to kill mildew.


--
Greed is the root of all eBay.
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