Week of 28 January 2008
Update: Sunday, 3 February 2008 10:20 -0500
I keep getting stuff done, but my to-do list keeps getting longer and
longer. This weekend, in addition to the laundry and other usual stuff,
I got wire shelving installed in the pantry cabinet in the kitchen and
on the back of the door into the dining room. Continuing the shelving
theme, I got most of the shelves installed on the end wall of my lab
and did some clean-up and reorganization there.
One of my
subscribers from earthquake country emailed me and asked if I planned
to include a wire or something across the front of the shelves to keep
the bottles from falling off. I thought about it, but I think they'll
be fine. The shelves are 3.5" wide, plus a half inch gap between the
back edge and the wall. I've secured each bracket (two brackets per
4-foot shelf) with three 1 5/8" drywall screws into the studs. They're
rock-solid. Each shelf is secured to its brackets by a screw driven up
through a hole in the bracket into the shelf.
Most of the
bottles that'll go on the shelves, and all of the bottles on the higher
shelves, are 4-ounce amber glass bottles that contain at most 100 mL of
(typically) pretty dilute solutions. The bottles are 2" diameter, so
there's plenty of space on the shelves.
Anything strong enough
to knock those bottles off the shelves would give us a lot more
problems than worrying about the bottles. I think the strongest
earthquake we've had in recent times is about 3.5. We do have tornados,
but again if we get nailed by something that bad we'll have more
important things to worry about.
Today, I'll finish installing the shelves in the lab and do more
clean-up down there. I need to get it cleaned up enough to use as a set
to shoot some videos.
also need to do some lighting and sound tests, not to mention figuring
out how best to shoot closeup video of reactions in test tubes and so
I also need to come up with an alternative for a
teleprompter. Most of the narration will be voiceover, but I'll do some
talking-head shots. For those, I have a couple of ideas. I may use the
traditional method: print the dialog in large type on both sides of
sheets of paper, and have Barbara hold them up as I read, dropping each
sheet as I finish it. Alternatively, I may just run a length of stiff
wire between the cabinets on either side just above the level of the
camcorder lens and use clothespins to suspend the dialog pages from it.
I finished installing shelves in the lab yesterday, so I now have 24
linear feet of additional shelf space. That frees up a lot of cabinet
The top three shelves are spaced to hold the four-ounce
(118 mL) amber bottles I use for most bench reagents, 22 per shelf.
When I need, for example, some potassium thiocyanate, it's much more
convenient to measure the required amount of potassium thiocyanate
solution than to weigh the solid chemical. All of the bench solutions
are made up to 0.01 M accuracy, which is sufficient for nearly anything
The fourth shelf has the same spacing as the first
three, but contains stuff like acid-base and redox indicator solutions,
special reagents like Dragendorff, Marquis, Scott, and Wagner reagents
(all for alkaloid tests), and so on. The fifth shelf is spaced to hold
the one-pint (473 mL) bottles that contain bench solutions of things
like dilute acids that I use more frequently or in larger quantities.
Finally, the sixth shelf has still wider spacing for storage of bulk
chemicals like 1 kilogram bottles of copper sulfate, sodium hydroxide,
I got email
yesterday from Dale Dougherty, the publisher of MAKE. He'd read the
recent articles about high levels of mercury in sushi, and wondered if
there was any practical field test for mercury. I replied:
Alas, no, that's not possible.
problems are that mercury is toxic at unbelievably low levels and that
it is a cumulative poison, which is to say it isn't excreted.
Accordingly, the allowable levels are set so low that there's no chance
they could be detected by any wet chemistry test with a sample of any
I was pretty sure of my facts, but just to be
certain I ran them past Paul Jones. His response was, "Maybe you could
use a wet chemistry test if you had an entire 500-pound tuna for your
sample, but otherwise you'd have to use instrumental tests."
Chervenak points out the Reinsch Test for mercury (which also produces
a positive for several other heavy metals). You dissolve the sample in
dilute HCl and put a copper strip in the solution. Any mercury present
plates out on the copper as a silvery mirror. The trouble is, if enough
mercury is present to produce a visible mirror with the Reinsch test,
that sample has enough mercury in it to poison everyone in a radius of
Dale replied, sending me a link to this site. To which I replied:
Cow! Someone whose saliva or urine tests positive with this kit is a
walking dead man. Again, one of the problems with heavy metals in
general and mercury in particular is that they bind tightly in the body
and aren't excreted. If your pee tests positive with this kit, you have
so much mercury in your body that you might as well just lie down and
Same deal with food samples. If you get a positive
test, there's enough mercury in that sample to poison a lot of people.
If you get a negative test, that's no indication that the sample is
safe to eat.
To give you an idea of just how little mercury is
hazardous, I just checked the numbers on allowable mercury intake,
which the FDA says is six micrograms per day. In other words, the gram
or so of mercury in a typical thermometer is enough mercury to match
the allowable maximum for an entire city of 167,000 people.
I get a spare moment, I may do the Reinsch Test just to determine the
threshold level of mercury needed to provide a visible mirror. My guess
is that it'd take at least a milligram of mercury in the sample, which
is the maximum permissible daily intake for 167 people.
Mary and I were talking about the Reinsch Test, she mentioned that
she'd bought a novel for Paul that I might like. That got us talking
about books, and I complained that I don't have time nowadays to read
as much for enjoyment as I'd like. I seldom finish even one novel a day
now, and sometimes I spend two evenings on one novel because much
of my evening reading time is occupied reading for work rather than for
pleasure. Mary said that wasn't surprising, since I'm now
doing two full-time jobs; writing books and doing the equivalent
of a graduate chemistry program. I hadn't thought about it that way,
but she's right. As usual.
Wednesday, 30 January 2008
More on mercury testing. When I talked to Paul Jones about this, one of
the first things he asked was, "can you do a flame test?" I replied
that that probably wouldn't work with a real-world sample, because the
mercury emissions would be swamped by emissions from other elements,
particularly sodium. (If there's any sodium at all in a sample, the
bright yellow sodium light overwhelms any other colors present.)
little background. When atoms absorb energy, electrons are
boosted to higher orbitals (energy states). The atom divests itself of
that additional energy when the electron drops to a lower orbital. The
excess energy is emitted as a photon at a specific wavelength.
Accordingly, each element has a specific characteristic spectrum, which
consists of lines of specific colors, and can be thought of as a
"fingerprint" of that element. In the visible spectrum, mercury
produces lines at 435.8 nm (violet-blue), 546.1 (green), 577.0
(yellow), and 579.1 (yellow).
If you vaporize a sample, say in a
gas burner flame, and examine the light produced with a spectrometer,
you'll see lines at those wavelengths if mercury is present in the
sample. Of course, unless the sample contains nothing but mercury,
there'll also be a lot of other lines that represent copper, sodium, or
whatever other elements are present in the sample. But if lines are
present at those wavelengths, you can be sure that mercury is present
in the sample, whatever else also happens to be present.
course, to see the lines you need a spectrometer. If you've ever seen
sunlight split by a prism into a rainbow, you understand the basics of
how a spectrometer works. Instead of a prism, a spectrometer uses a
diffraction grating to split the incident light into its component
wavelengths. That spectrum is displayed against a scale so that you can
determine the wavelength of each line. By comparing the wavelengths
present against a list of the wavelengths produced by each element, you
can determine which elements are present in the sample.
problem is that flame spectrometers aren't cheap. Or so I thought,
until I started looking around yesterday. I knew I could buy a
diffraction grating for a couple of bucks. That would produce line
spectra, but without calibration those spectra would be useless for
identifying specific elements. Then I happened across this.
that. A $25 flame spectrometer. Well, you have to supply your own
flame, but that's easily addressed. But the important part is that it
provides calibrated spectra that can be used to identify specific
elements in a flame. The sample images give you an idea of what line
spectra look like. Hydrogen, at the top, clearly shows the H-alpha and
H-beta lines. Sodium, in the middle, clearly shows the intense yellow
lines characteristic of sodium. (The image at the bottom, also labeled
This little $25 device may look like a
toy, but it's actually a serious scientific instrument. Obviously, it's
nowhere near as sensitive or accurate as the $25,000 flame
spectrometers found in professional labs, but it'll serve for our
purposes. So I ordered one.
I'll use it in the home forensics
lab book to illustrate how flame spectroscopy is used in forensics
investigations. And, who knows, some of the young people who get their
first experience with flame spectroscopy in their home forensics labs
may in ten or fifteen years be using those $25,000 flame spectrometers
in real forensics labs.
Hmm. John Edwards just announced that he's dropping out of the race for
the Democratic nomination for president. That leaves them with two
candidates in the running, neither of whom is electable. Clinton is so
intensely hated by considerably more than half the electorate that she
has no chance to win a majority of the popular vote, let alone the
electoral vote. And what are the chances that a man named Barack
Hussein Obama could ever be elected president? Unless Ron Paul turns
out to be the spoiler.
Things are likely to be interesting in
November. The Democrats will run Clinton or Obama, it doesn't matter
which. The Republicans will probably run McCain, who is at least
electable. And I think it's very likely that Ron Paul will run as an
independent. If so, he'll likely hurt McCain more than the Democrat
candidate, possibly throwing the election to the Democrats.
Thursday, 31 January
- It's nice to know that my journal page is occasionally of some practical use to readers.
From: Steve Sanders To: Robert Bruce ThompsonDate: Wed Jan 30 23:35:46 2008 Re: Thanks for Saving Me A Service CallBob,Our
gas logs have not been working for the past few days and it has been
cold (single digits F in the am) in the St. Louis area. The pilot light
would come on, but it was a more yellowish flame and wouldn't stay lit.Tonight, I did a Google search on "gas logs won't light" and one of the hits I got was www.ttgnet.com/daynotes/2002/2002-49.html.I
looked at your site, which I have been following since you started, and
read what the service technician told you on 9 December 2002. I used a
straw to blow the pilot light area clean. I then lit the pilot light.
There was a strong, blue flame that stayed lit. The logs then fired up.Thanks again. You saved me a few bucks.
always interesting when, from the entire Internet, a Google search
turns up what one is looking for on a site that one regularly reads. I
had the same experience a few years ago when I was trying to get my
sister-in-law's Brother MFC-4800 printer running under Xandros Linux.
The first hit that Google turned up for her printer model was one of Brian Bilbrey's journal pages. Until that moment, I had no idea that Brian owned that printer model.
UPS showed up yesterday with the spectrometer, so I spent some time
playing with it. It works as advertised, although it's a bit finicky
about eye positioning. Last night, after we walked the dogs after
dinner, Barbara and I spent a few minutes looking at different light
sources--an incandescent lamp, a standard fluorescent tube, a compact
fluorscent bulb, a streetlight, my computer LCD display, and so on.
pretty neat seeing the differences in the continuous spectra of some of
those sources and the emission lines on others. For example, I just
looked at a white area of my LCD display. There are three distinct
lines, a broad, fairly dim blue line centered on about 490 nm, a
bright green line at about 546nm, and a bright red at about 611 nm.
There's also a much dimmer but sharp blue line around 436 nm, and a
quite dim yellowish line around 578nm. Obviously, mercury is present in
the LCD backlight. Moving the spectrometer over to the CFL in my desk
lamp shows an identical spectrum, so it's clear that the LCD backlight
uses exactly the same technology as the CFLs.
spectrum light sources are also interesting. Yesterday, I pointed the
spectrometer at a brightly lit cloud. (Never point any optical
instrument directly at the sun, which can blind you in an instant.)
There were no lines visible, just a continuous bright rainbow from deep
red on the left to deep violet on the right, with the brightness
gradually tapering off at both ends. I'm sure the actual brightness
doesn't taper off. It's just that my eyes lose sensitivity at the
extreme ends of the visible spectrum.
When I pointed the
spectrometer at an incandescent bulb, the difference was obvious. The
spectrum was continuous, but not equally bright across the range. The
left side of the spectrum, the reds and yellows, was very bright. The
greens in the middle were a bit dimmer, and the blues much dimmer
still. The violets were almost invisibly dim. It's obvious why
incandescent lighting appears yellow-orange. There just isn't much green
being emitted, and even less blue.
To get true full-spectrum
light from an incandescent bulb, they'd need to boost the temperature
of the filament from the 3200 K they use now to about 5500 or 6000 K.
To do that, they'd have to replace the tungsten filament with some sort
of ceramic, I suppose. Either that, or settle for a very short bulb
Saturday, 2 February
- Dinner with Paul and Mary last night.
is getting ready for a working trip to Hawaii, where he'll be
harvesting sea slugs as a part of his current project. Paul is an
organic chemist with special expertise in photochemistry. I'm probably
not getting this quite right, but apparently Hawaiian sea slugs consume
algae and incorporate the chlorophyll, which
remains photosynthetically active in the sea slug's body. I'd
always thought that only plants used photosynthesis, but apparently
there a few animals that do so, and Hawaiian sea slugs are one of them.
suggested to Paul that he could save money by using common ordinary New
Jersey sea slugs, but he claims there aren't any sea slugs in New
Jersey. Furthermore, by an incredible coincidence, the types of
sea slugs that Paul needs for his work are found only in resort areas
around the world, so he has no choice but to spend lots of time at one
or more of these resorts. I told Paul that I believed him, but
As always, I learned something during the
dinner conversation. This time, it was that the super bowl is being
played this evening, although I still don't know which teams are
playing or why I should care. Also as always, the conversation was
very wide-ranging, from politics and sports and chemistry to methods
for reducing the likelihood of eclampsia and the recent news articles
on human parthenogenisis.
The pope ain't gonna like it, but it
seems likely that before long lesbian couples will be able to be the
natural parents of children for which one provides the ovum and the
other the sperm, produced from stem cells in her bone marrow. Of
course, since the two female parents have only X chromosomes, all
children conceived by such couples will be female.
will be able to do the same thing, assuming they can find a host
mother. Children conceived by two male parents will be one quarter
female (XX), one half male (XY and YX), and one quarter monsters (YY).
most intriguingly, there'll be nothing to prevent one person from
contributing both ovum and sperm. I expect that religious people and
politicians will fight that idea tooth and nail, presumably on the
basis of prohibited consanguinity.
need some decent lights for shooting video. I checked the B&H
catalog, which has a wide range of video lights for studio work, but
the prices for professional studio video lights start with a couple of
zeros on the end and climb quickly into the stratosphere. So I made a
quick trip to Lowe's, where I bought a couple of 500W quartz-halogen work lights for $15 each. If the light is too harsh, I'll just bounce them off a couple of large white cards.
This afternoon, I'm doing a phone interview with the Amateur Observers' Society of New York about Illustrated Guide to Astronomical Wonders.
I've done lots of phone interviews with radio stations, but this will
be the first I've done with an astronomy club. I'm looking forward to
1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 by Robert