This is 2nd English edition, and L.P.C does state in the foreword that
references have been intentionally left out.

I searched through the book again, and found that the original paper
is by Lumiere and Seyewetz, 1905.

Here is the exact text :

"It should, moreover to be noted that several developers, particularly
HQ and paraminophenol), if added i very minute quantity to a solution
of sulphite, retard very markedly the oxidation of the latter by
oxygen of the air(Lumiere & Seyewetz, 1905). They probably oppose the
catalytic action of various metallic salts, especially copper salts,
which may be present in quantities so small as to escape detection"

In another page, he states the quantity of developer to be added as 5
gr ( I think grains) to 20 Oz of sulfite solution.

Perhaps this is no longer of practical significance.

I find this book really fascinating.

thanks,
Sreenath


On Jun 20, 3:56 am, "Richard Knoppow" wrote:
"Jean-David Beyer" wrote in message

news:5vQdi.3275$lY5.1258@trnddc07...



Richard Knoppow wrote:

One problem with Clerk is that there are no
attributions or
citations. Sulfite slowly absorbs oxygen becoming Sodium
Sulfate. In a
developer or fixing bath its affinity for oxygen is used
to protect
other chemicals by preferential absorption. Hydroquinone
and Metol are
also oxygen absorbers but, like you, I've never heard of
adding any
to a Sulfite solution to preserve it.
Generally, the more concentrated a sulfite solution
it the longer
it will last. Probably the best way to preserve a sulfite
solution is
to keep it in a closed, sealed container of some material
which does
not allow air to pass through. Glass is best but some
high density
plastics are nearly as good.
The various editions of Clerk's books have a lot of
good stuff
in them but, IMO, the lack of citations and references
severely limits
them.

The only copy of L.P. Clerc I have seen is an English
translation in two
volumes. These seem to be intended for English students
who want a career in
photography. I know some color illustrations (all of them)
are missing,
though referred to in the text. Could it be that a French
edition would
contain the citations? L.P.Clerc was a scholar, among
other things, and it
seems unlikely that he would have left out the citations.

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