"Rodger Whitlock" wrote in
message ...
On Wed, 6 Aug 2003 08:43:15 +0000 (UTC), Franz Heymann wrote:

I would now love to hear an explanation of why the package of Miracid
says
quite clearly
"Soil Acidifier Plant Food".

Because (a) it's chemical makeup is such that it acidifies the
soil -- but just how much and under what conditions remains
unstated;

If it really is capable of acidifying the soil, I would have thought that it
must contain an acid. I am still ignorant of what the acid might be.
I have just done a quick test with a piece of litmus paper in a solution of
Miracid roughly 5 times the recommended strength, and the paper colour is
hardly any different from that of neutral water. I am beginning to have my
doubts about the claim that it is a soil acidifier.

and (b) it contains primary plant foods.

There is no doubt about that.

Someone else replied by email pointing out that the box says
"contains phosphorous pentoxide in a neutral ammonium citrate
solution".

I wish folk would respond to items in this newsletter by contributing to the
newsletter. In any case, the reply is inaccurate. My Miracid is not a
solution at all. It consists of granules. The box axtually says (and I
quote)
"Phosphorus Pentoxide P2O5 soluble in neutral ammonium citrate and in water
10% (4.4%P)"
My guess is that the box is simply trying to say that there are 10% soluble
phosphates in the product, with the phosphate content measured in terms of
the relative amount of phosphate ion in the product.

If I may hark back to my earlier faux pas about stating that the P2O5
referred to an actual phosphorus pentoxide ingredient: I should have
realised that I was talking nonsense in a fit of depravity, because I have
handled P2O5 for decades as a drying agent in vacuum systems. It is an
intense hygroscopic and frighteningly corrosive substance, quite unsuitable
for use "as is" in a gardening chemical. I can blame only my steadily
advancing senility for my mistake.

That may be a statement of how they make the stuff,
but it's not a statement of what's in the box because of the
interactions of the ingredients, esp. phosophorus pentoxide in
solution. Nick McLaren's chemistry may be less rusty than mine
and able to elucidate this.

While perhaps it's true that legally speaking, "contains" means
"we made it out of X", FH's misapprehension that "contains
phosphorus pentoxide" meant just what it said led to a
misunderstanding of the actual chemistry.

Yes, indeed.

My email correspondent also mentioned that the box uses the word
"sequestered", but also "chelated".

[Franz Heymann]