"Martin Brown" wrote in message
Bertie Doe wrote

The following are US capacity measurements:
http://preview.tinyurl.com/34gjnw2

"A 4-ounce solution of 2 percent caffeine applied to
the soil of 4-inch
greenhouse pots devastated garden slugs"

I assume they mean 4 oz of coffee contains 2% of
pure caffeine. We have
to speculate as to the strength and type of coffee
and amount used.

I wouldn't assume that at all. 4 oz of coffee will
likely contain 0.03-0.06g of caffeine. Taking 4oz as
roughly ~100g = 0.05% caffeine content. A 2% caffeine
solution would be very very strong coffee the sort
that you could stand the spoon up in.


You're right 2% pure caffeine would give a hippo the
jitters. I think I was getting confused with 2mg which
is your usual consumption in a cuppa Joe.

Espresso coffee can contain up to 2g/Litre caffeine
which is 0.2%!

Agreed, but I still think it's worth persuing further,
the ScienceNews article mentions:-
"Even concentrations of only 0.1 percent caffeine may
prove useful. Sprayed onto such slug-prized cuisine as
cabbage leaves, those concentrations deterred feeding
by 62 percent, respectively, when compared to
uncaffeinated salad greens".

In Spring when I top-up my stash of green unroasted
coffee beans, I'll include 250g of the stronger
(cheaper) robusta, in my order. Somewhere I read that
roasting reduces some of the caffeine content - so I'll
grind, add hot water and leave it to steep for a couple
of days. Filter it, then use it solely on my salad
stuff. The brassicas can look after themselves!!

Bertie