Hi

Platinum RTD's are a pretty good bet for -80C, they hold up well down there. For calibration, ammonia and acetylene both have triple points in the vicinity. I'd probably try ammonia first, but not for any good reason. Triple point cells aren't all that hard to make. Never tried it with something flammable ...

Bob

On Jan 26, 2013, at 12:32 AM, Chris Albertson albertson.chris@gmail.com wrote:

Il 2013-01-26 14:58 Bob Camp ha scritto:

Doesn't acetylene have a bad habit of dissociate when pure liquid?

Fabio.

For microscopes and all related topics, the Yahoo Microscope Group is very
knowledgeable. It has over 3500 members now.

-John

=================

Hi

Sounds like a good reason to avoid it.

Bob

On Jan 26, 2013, at 10:28 AM, Fabio Eboli fabioeb@quipo.it wrote:

Trying to play with liquid acetylene is like juggling operating chainsaws.

-John

================

If the intent is surface mount work, get an old B&L Stereozoom 3. I'd suggest getting one with any attached illuminator, even a broken one, since the fitting to hold the illuminator is about $30. Later model stereozooms had plastic parts in the focus mechanism.  If you need more magnification, you can always get "stronger" occulars.

-----Original Message-----
From: "J. Forster" jfor@quikus.com
Sender: time-nuts-bounces@febo.com
Date: Sat, 26 Jan 2013 09:04:59
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: jfor@quikus.com, Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] OT, looking for a good science forum

For microscopes and all related topics, the Yahoo Microscope Group is very
knowledgeable. It has over 3500 members now.

-John

=================

time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Maybe wrong search words;
There may be pearls in here:
http://www.goedonline.com/101-websites-for-science-teachers
Don
DARRELL ROBINSON

--
"Neither the voice of authority nor the weight of reason and argument
are as significant as experiment, for thence comes quiet to the mind."
De Erroribus Medicorum, R. Bacon, 13th century.
"If you don't know what it is, don't poke it."
Ghost in the Shell

Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
www.lightningforensics.com
www.sixmilesystems.com

Or perhaps:
http://www.scienceforums.net/forum/78-amateur-science/
Don

Don Latham

--
"Neither the voice of authority nor the weight of reason and argument
are as significant as experiment, for thence comes quiet to the mind."
De Erroribus Medicorum, R. Bacon, 13th century.
"If you don't know what it is, don't poke it."
Ghost in the Shell

Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
www.lightningforensics.com
www.sixmilesystems.com

On Sat, Jan 26, 2013 at 10:00 AM,  lists@lazygranch.com wrote:

This is really OT for the TN list.  But no.  I'm looking to equip a
biology lab.  Need a compound microscope that has on the high side a
1000x magnification.  Pretty much your "Standard" university lab
microscope that all freshmen bio students would use.  These are a
little hard to know what's best to get

But I think in addition I want a stereo microscope too.  There are
decent new ones from China for under $100 and older ones like you
mentioned for about the same price.  New ones are attractive because
of advances like battery powered LED illumination.  This kind of
microscope is pretty easy to find compared to the other.

Chris Albertson
Redondo Beach, California

The microscope group can help with reccomendations. 1000x is really
pushing it, because of 'empty magnification'.

Best,

-John

==================

The stereo boom mount scopes from amscope are priced right. The one I have seems well made and works great for surface mount work down to 0201. Some of the finish details are a bit off (generic metal adjustment handles) but it was a new, complete, guaranteed working scope so I don't have any legitimate complaints.

If you are going to buy one, buy it from amazon after figuring out which on you want on the amscope site. You'll pay less

Eric

Sent from my Banana Jr.(tm) mobile device

On Jan 26, 2013, at 1:36 PM, Chris Albertson albertson.chris@gmail.com wrote:

On Sat, Jan 26, 2013 at 1:46 PM, J. Forster jfor@quikus.com wrote:

1000x is the "standard".  Almost every microscope in a biology lab
will have a 100x oil immersion objective and a 10x eyepiece.  And
then also have two or three lower power objectives as well.

If you were to try and get 1000x from a 40x objective or if the
optical quality were poor, yes, then you are just getting big, blurry
images with no more detai than you'd see at 400x.  That is what you
call "empty magnification" and it is.

It turns out that 1000x is about the limit of light microscopes and
you pretty much need that if the goal is to see structures inside a
cell, rather then just the cell's outline.  You need to use oil that
has about the same refractive index as the glass cover slide.  In
high school level labs they use cheaper 400x scopes and just look at
larger stuff.

Chris Albertson
Redondo Beach, California

On 26 January 2013 18:31, DARRELL ROBINSON darrell@shaw.ca wrote:

Make that three.

Dave

I like the idea of a "amateur microscopy nuts" reflector.

After a warm day, my bees took their cleansing flights and I collected
some of their poop to look for parasites.
Did not find anything moving at 500x , like tracheal mites or their
parts, but I did find a lot of undigested pollen.

I have not found a reflector for my microscopy interests.

Stan, W1LE

On 1/26/2013 5:45 PM, David Kirkby wrote:

The Yahoo Microscope Group already exists with over 3700 members world
wide, which forms a huge knowlege base, from biology to microelectronics.

http://tech.groups.yahoo.com/group/Microscope/

Why re-invent the wheel?

-John

==========

Thanks for the pointer. I am checking it out now.  Stan

On 1/26/2013 8:59 PM, J. Forster wrote:

Try a AO PhaseStar phase contrast microscope they are relatively cheap on eBay and they should be more than adequate for beekeeping. The phase contrast feature allows you to see celluar details without staining in most cases
Most of them have fittings for camera tubes so photomicrography is easily accomplished or use a video camera and a large monitor for studying details or group viewing

Sent from my iPhone

On Jan 26, 2013, at 4:36 PM, Chris Albertson albertson.chris@gmail.com wrote:

I've read a lot on sciencemadness.org, which as Bob Said, leans heavily
toward chemistry.  They seem to have quite an interesting an thriving
community.

-Jeff
W7WWA