Robert wrote:
"Franz Heymann" [...]
No, an elementary knowledge of chemistry, aided by a few hundred
references in Google says I am right.
Biulders' Lime really is Calcium Hydroxide, known as "slaked
lime"
It is an alkaline material which is very frequently used to treat
acid soil.

Franz
We'll have to agree to differ, my searches and the GQT team back me
up but who cares really lol. All the best

But every gardener _should_ care; and it isn't a "lol" matter. What
searches? What exactly did which members of the GQT team say about
it?

I've just done a very swift (admittedly _very_ swift) Internet
search, and the nearest thing I found to your position is a site
which specifically recommends that builders' lime should not be used
in desilting operations because it may contain impurities which could
upset the chemical balance of the environment to be treated. A quite
separate issue from the material's garden value.

Just as I believed, there are, or perhaps have been, perceived to be
roughly two grades of hydrated lime, and in trade they are, or
perhaps have been, sometimes distinguished as "slaked lime" and
"hydrated lime"; but this is a convenient traditional distinction,
not a scientific one. I'm still quite sure that "builders' lime" is
not quicklime, which is a bugger to store safely; I find that Build
Centre don't appear even to stock it, though they do stock two brands
of hydrated. (I'm sure they could get it for you, of course.)

Hobby-horse/
This "Who cares really?" is a suicidally bad habit the British need
to grow out of. For some reason a country which _excels_ in academic
and scientific research and music -- all disciplines in which
precision is of the very essence -- also has a culture which derides
precision (note the use of such insults as "anorak" and "pedant" from
top to bottom of the society). Perhaps it's a healthy balance, but I
don't think so: more a "them and us".
/Hobby-horse

I'm sorry to go on and on like this, but I've got the bit between my
teeth!

Mike.