"Franz Heymann" wrote in message ...
"Martin Brown" wrote in message
...
[...]
There are more cunning ways to measure humic acids.

I don't doubt that. By the way, I don't like the catch-all term
"humic acids".

Well, now that we've disposed of the undoubted scam, in particular
applications catch-all terms may have their uses. For example, the
concentration of acidic humic compounds in a water sample is of
serious and proper interest, and most of the time no more specific
term is needed -- in fact, listing the compounds out would often be a
waste of space. I've just looked for another example, and at once
found an on-line oil-industry glossary which suggests that, at least
for one phase of that industry, the term's good enough for practical
purposes:

quote/humic acid

1. n. [Drilling Fluids] ID: 1986

Organic carboxylic acids of complex molecular structure (aromatic and
phenolic) that comprise 10 to 90% of lignite. Humic acids in lignite
react with caustic ingredients (NaOH and KOH) in mud. The water
solubility of lignite depends on its humic acid content.
Decarboxylation of humic acid groups by hydrolysis in alkaline muds is
a major source of carbonate and bicarbonate anions in water muds.
/endquote

You could afford to forget more about this than I shall ever have
known, but it seems to me that even such ordinarily useful expressions
as "fatty acids" or "amino-acids" could also be called "catch-all
terms".

(Deep breath.)

Mike.