On 15/04/16 16:20, Chris Hogg wrote:
On Fri, 15 Apr 2016 11:10:54 -0400, S Viemeister
wrote:

On 4/15/2016 10:43 AM, Chris Hogg wrote:
On Fri, 15 Apr 2016 14:45:44 +0100, "Dan S. MacAbre"
wrote:
A level standard teaspoon holds 5ml, which
will be about 5g of ammonium sulphate, so three level teaspoons per
sq.metre will be roughly right.

Are you quite certain on that measurement? 5ml of _water_ weighs 5g -
but I'd be surprised if 5 ml of ammonium sulphate does.

I'm assuming that the ammonium sulphate is loose packed, so would have
a lower density than the pure solid. As a rough check, 5ml of loose
potassium chloride weighs 5.5g. Within the accuracy needed for such
things (it's not analytical chemistry, after all) assuming a
loose-pack density of 1g/ml is probably quite good enough.

I note also that Jeff recommended a similar amount, although he did
say three slightly heaped teaspoons.

Indeed - I waved an informed finger in the air!!

According to Wikipedia the density of ammonium sulfate is 1.77.g/cm^3
(the density of potassium chloride is a little higher - 1.98). But of
course that would be as a single lump; in that case, 5ml of ammonium
sulfate would weigh just under 9g. It's the bulk density we are really
interested in and that depends on a lot of things. But, as you and I
agree, it's not exactly critical.

--

Jeff