"K Barrett" <[EMAIL PROTECTED]> queried thusly:
>Ok, thanks AJ! Any input on the notion that peroxide encourages root
>branching?? I've seen research about roots curving around bacteria attached
>to the developing root surface, but nothing about root branching per se.
Alas, I have nothing intelligent to say beyond my own experiences
with peroxide on seedlings.
"Giles Smith" <[EMAIL PROTECTED]> queried thusly:
>For a long time most inexpensive humidity guages were not noted for their
>accuracy and precision. Recently a number of inexpensive electronic
>instruments have appeard on the market (Oregon Scientific is a major supplier,
>but all of their units are actually made in China). Does anyone know how
>accurate these units are? They read to a tenth of a percent, but I would be
>happy if I could be confident they were accurate to within five percent. I
>broke my sling psychrometer and have no ready method of calibration. Any info
>appreciated.
I could write volumes on humidity measurement, but I'm going to
skip that. Aside from the techniques originally described by Robin Stokes
(last at University of New England in Australia) using gas chromatography,
sling psychrometry is going to be your best bet. However, there is no need
to use the sling psychrometer in the manner implied by the name: purchase
two alcohol thermometers of reasonable accuracy, and attach them side by
side to a board. One thermometer should have its bulb sleeved with a cotton
wick; the end of this is placed in distilled or RO water. Put the board in
front of a fan in the greenhouse. Compare the wet bulb temperature to the
dry bulb temperature with a psychrometric chart downloaded from the web.
Cackle at having saved about a hundred bucks from a science supply company.
One company sells a self-contained version of this, replete with
fan, for about $300. American Science and Surplus (www.sciplus.com) sells
alcohol thermometers for $3.50. Make sure the cotton sleeve gets all the
way up to the calibration line for greatest accuracy.
As an aside, I used to have a chemistry job where life safety
relied upon humidity being within certain parameters. Dial hygrometers were
not to be trusted. We tested with sling psychrometers. It was also duly
noted that when glassware containing icewater didn't sweat, all work was to
stop since the humidity was too low to continue safely. IIRC, that worked
out to 25-30% RH at normal working temperatures, which is way too low for
what we were doing.
Cheers,
-AJHicks
Chandler, AZ
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