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August 3, 2009

Melting point tester
Posted by Teresa at 02:53 PM *

Would anyone within earshot know of a working melting point tester the owner would be willing to sell for cheap? A friend of mine is looking for one.

Comments on Melting point tester:
#1 ::: John Stanning ::: (view all by) ::: August 03, 2009, 03:48 PM:

OK, I have to ask.

Do you really mean a melting point tester?  Or is “melting point tester” code for something so strange that I shouldn’t want to know?

#2 ::: James D. Macdonald ::: (view all by) ::: August 03, 2009, 04:49 PM:

You mean a Thiele Melting Point Tube? You should be able to pick one up at any lab supply house for around ten bucks.

You'll also need: a bunsen burner, a thermometer, a stand with a clamp, whatever fluid (often mineral oil), a two-hole stopper, and small capillary sample tubes.

#3 ::: Charlie Stross ::: (view all by) ::: August 03, 2009, 05:40 PM:

Do not, whatever you do, test it on N60.

#4 ::: Diatryma ::: (view all by) ::: August 03, 2009, 07:17 PM:

Huh. I would have put money on American Science and Surplus, for no good reason except that they have so much random stuff. I'll try to remember the next time I'm at UIowa Surplus.

#5 ::: Kieran ::: (view all by) ::: August 03, 2009, 08:16 PM:

Normally I'd be happy to oblige but we just moved away from Tucson. I could do you a humidity test.

#6 ::: Tom Whitmore ::: (view all by) ::: August 03, 2009, 09:26 PM:

What exactly are you interested in finding the melting point of? If it melts in a fairly wide temperature range, the simplest thing to do is stick a thermometer in a sample and let it solidify. The melting and the solidifying points should be the same (to within a fairly small standard error). And what precision is needed? In general, more precision = more $.

#7 ::: Matt Austern ::: (view all by) ::: August 03, 2009, 11:36 PM:

Yep, I was wondering the same thing Tom was. A candy thermometer would make a pretty good melting pointer tester, assuming you've got something that melts in a range of about 100 to 200 °C.

#8 ::: Matthew Austern ::: (view all by) ::: August 03, 2009, 11:39 PM:

Hm, I see I typoed. I kind of like the phrase "melting pointer tester", though. I should probably figure out something for it to mean. Maybe some kind of C++ static analysis tool to prevent memory corruption?

#9 ::: Michael Roberts ::: (view all by) ::: August 04, 2009, 12:13 AM:

Matthew @8: a pointer tester as designed by Dali? Bonus if there is a reallllly tall giraffe on the horizon.

#10 ::: PhilPalmer ::: (view all by) ::: August 04, 2009, 05:24 PM:

I'm guessing that this melting point tester needs to be of clinical accuracy and sorry, I haven't got one.

#11 ::: dave Howell ::: (view all by) ::: August 05, 2009, 03:45 AM:

James @ 2: The difference between a melting point tester and a Thiele tube is that the only other component required of the tester is a capillary tube to contain the material being tested.

Tom@6: Actually, what MPT's test are, in fact, substances that are supposed to melt all at once and nothing flat; generally powdered crystalline substances. The more impure, the broader the temperature range between "begins to melt" and "visible meniscus." Apparently they were fairly common in the 70's and 80's, used by people testing their cocaine. In later years the coke sold on the street was cut so full of crap that testing it was futile, and of course the crack form wasn't suited to an MPT.

Phil@12: Does anybody even make a non-clinical-grade melting point tester? Even the rumored cocaine home-testing kit appears to have been adequately functional.

I think sometimes Teresa is a bad influence. She makes some off-the-cuff comment, I start Googling merrily away, and a few hours later, I suddenly realize how many strange new facts have come into my possession. . . .

#12 ::: abi ::: (view all by) ::: August 05, 2009, 03:55 AM:

Dave Howell @13:
I think sometimes Teresa is a bad influence.

Fixed it for you.

#13 ::: Margaret Organ-Kean ::: (view all by) ::: August 08, 2009, 06:36 PM:

Would this have anything to do with a tube furnace? I think I have one (a tube furnace) and I'd like to make it go away, preferably for money.

#14 ::: David Harmon ::: (view all by) ::: August 08, 2009, 09:19 PM:

Dave Howell #13: She makes some off-the-cuff comment, I start Googling merrily away, and a few hours later, I suddenly realize how many strange new facts have come into my possession. . . .

And just how is this a "bad influence"?

#15 ::: Jordin Kare ::: (view all by) ::: August 10, 2009, 03:52 PM:

Actually, I don't have one but I may be able to get one on a time scale of 3-4 weeks, if said friend isn't in too much of a hurry. They show up fairly often on some technical auction sites.

#16 ::: Jon Hendry ::: (view all by) ::: August 12, 2009, 01:20 AM:

abi @14: "Teresa is a bad influence."

Teresa is a wonderfully bad influence.

Fixed that for you.

#17 ::: Bruce E. Durocher II ::: (view all by) ::: August 12, 2009, 01:48 AM:

As the person who brought home the tube furnace that Margaret is trying to get rid of I'd be even happier if it went away, preferably for money, since I'd quit feeling bad every time I looked at the damn thing...

Hey, Dave! Ever considered what a nifty accessory a tube furnace would be for a Packard Clipper?

#18 ::: ppint. ::: (view all by) ::: August 15, 2009, 07:52 PM:

depending on the temperature range over which the substance[s] being checked melt or sublimate, it's not too difficult to make up your own; the main consumables are closed-at-one-end capilliary tubes makeable from ordinary soda glass tubing with use of a bunsen burner or similar, and the gas, electricity or whatever used to supply controllable steady heating. you/they will also need a suitable [temperature range, sensitivity and accuracy] thermometer [or other sufficiently accurate temperature-measuring device] and a transparent air, water, metal-with-strategically-placed-hole[s] or oil bath, to convey the heat to the test sample capilliary tubes and thermometer [or whatever] simultaneously, and something to hold everything else in place [lab retort stands, clamps, whatever available works]. plus adequate shielding against draughts.

otoh the nearest friendly physics/chemistry university lab technician may be able to make a "real" one available - so long as you wear a white or brown lab coat...

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