Sciencemadness Discussion Board

Reduction tube, vented boiling tube

JScott - 7-9-2018 at 07:00

I would like to perform the reduction of Iron III in hydrogen.

I have seen this done in a "boiling tube". Something like a heavy test tube with a vent at the closed end. I have also seen this done in a "reduction tube" a narrow version of the same.

In both cases the glass is much thicker than anything I have here, leading me think that creating it from glass I have won't work well.

I've checked out my normal glassware sources, Dr. Bob's spreadsheet, and a done a number of searches.

First time I've been stumped looking for an apparatus, I'm sure it won't be my last. Do any of you know of a source for glassware that might stock these?

Ubya - 7-9-2018 at 08:33

maybe you are looking for something like this

JScott - 7-9-2018 at 10:49


That's darned close to a boiling tube, but not heavy enough. The one's I've seen and then read about talk about a large scale test tube with glass much heavier.

The other, the 'reduction tube' may be very similar to a part used on some rotovaps though I don't know it they are of the same gauge glass either.

If I can find no other, at least that has a port to show hydrogen flame color and size at the sealed end of the tube.

Thanks for getting back to me, and thanks for the new addition to my bookmarks!

[Edited on 9-7-2018 by JScott]

Dr.Bob - 7-9-2018 at 11:17

I have many Ace and Chemglass heavy walled tubes for high pressure reactions, from 10 ml to 250 ml. What I don't have is many caps or top fittings for them, so if you just want to use a tube (they are all threaded on the top with Ace type threads) and try to find the right fitting for them, let me know. I do have some fittings, just not sure which are good for what. But the tubes are rated for several atm of pressure ( I thin up to 100-150 psi, maybe higher), assuming that you can seal them properly and such. See the link below for examples:

Chemglass has some similar products.

JScott - 7-9-2018 at 12:43


This is what I'm trying to do.

Will your tube fit the bill? I should have written you, but I did check your list first. I don't expect high pressure, but it will be a high temperature reaction.

One of the those links doesn't work, and one brought me to a tube that was threaded on one end. It is important that the glass be heavy due to direct exposure to the flame I think.

[Edited on 9-7-2018 by JScott]

[Edited on 9-7-2018 by JScott]

Ubya - 7-9-2018 at 15:55

but it's not cheapi understood what you want, the tube is thick walled but if the heat is enough borosilicate will soften, you need fused quartz

JScott - 8-9-2018 at 03:46

Wow, thank you! I was thinking I would never see one for sale. So much for Goggle and Duck, Duck Go. I guess search engines can only take you so far.

You are right, it's not cheap, but that's what piggy banks are for. Life is short, if you can't break the pig now and again, what's the point?

I also thank you for yet another valuable book mark. I wonder why search engines ignore these sites?

Ubya - 8-9-2018 at 03:56

use google images;)

Dr.Bob - 8-9-2018 at 05:35

If you want to heat it with a flame or to ridiculous temperatures, quartz is the way to go, the pressure tubes are only rated to about 200-300 C, depending on type and use. Also, thicker glass is much less resistant to flame heating than thin glass, as the difference between the inside and outside temperature of thick glass creates stress, so thick glass works much better with gradual and gentle heating.

But quartz can handle heat stress even better. The tubes from Perkin Elmer look made for elemental analyzers, and might be too small, depending on your scale.

There is a company called prism glass that also does quartz work, which might be more approachable for custom work or dealing with individuals. They are here in NC, but there are a few other small quartz shops in the US, just google quartz fabricators or the like.

If you have a specific item you want, they might be able to help.

If anyone is interested in pressure tubes, I can try to make a list sometime, most are in a couple of boxes right now.

[Edited on 8-9-2018 by Dr.Bob]

JScott - 9-9-2018 at 08:57

Dr. Bob,

I will probably spring for that quartz tube you showed me sometime in the near future. That is providing that company will set up an account for an amateur. Having survived on mostly Chinese glass I haven't had to go through any formalities in the past.


I thought I had used Goggle images, but if you've found one for sale that way I must have bunged it up somehow ;-)

Thanks everyone for your help.

JScott - 18-9-2018 at 15:42

Ah, so close but no cigar! That reduction would have been perfect.

Should anyone else be interested, I haven't been able "shop online" without an account number.

Though I'm sure if I call them in the morning and explain I am home experimenter they will forgo any of the aforementioned formalities. ;)


Then I find this! That is the very item listed on the manufacturer's site.

But, you couldn't order it there it either. The details in the listing don't match the listing header. The photo shows five tubes and there is not way to pick what one will be sent. There is no place to write the manufacture and we know how well Amazon customer service will do with this.

I could just order it and keep my fingers crossed, but then there is three week wait as well. So, wait three weeks, send it back to Amazon... no, that won't work either.

Since I've rearranged my search query to include the word quartz I have found a great deal more. So, I'm closing in!

[Edited on 9-19-2018 by JScott]

SO exicited!

JScott - 21-9-2018 at 04:37

Hmmmm, seems as though I may be talking to myself at this point, but if anyone else is looking for a tube like this...

I ordered it, used the item number from the Amazon listing on the manufactures site and it looks like Amazon will ship a tube with the correct configuration.

Says it will take 3-4 weeks...hmmm. Making them one at a time perhaps? ;-)

Can't wait to post a photo of my newly acquired tube!

Ubya - 21-9-2018 at 05:29

happy to see that in the end you succeeded :)

JScott - 21-9-2018 at 15:46

Quote: Originally posted by Ubya  
happy to see that in the end you succeeded :)

I followed the link you sent me Perkin Elmer. They sell through Amazon also.

Thanks for your help!

Amos - 22-9-2018 at 09:38

What compound of Iron(III) are you trying to reduce? Any salt can be reduced in aqueous solution just by adding metallic iron and stirring.

morganbw - 22-9-2018 at 16:09

I bought a few pieces of quartz tubing from deschem. I have a somewhat similar use for the quartz tubes as you. I probably will attempt to make AlCl3 using one of them sometime in the future.
This was the description.

500mm, Quartz Glass Tube, OD 18mm,1.5mm Thick, Made From Fused Silica,3Pcs/Lot
Total Length is 500mm
Outer Diameter is 18mm
Inner Diameter is 15mm
Thickness is 1.5mm
Made From Quartz Glass
Quantity:3 pcs/Lot

[Edited on 23-9-2018 by morganbw]

WGTR - 23-9-2018 at 09:03

Have you tried using borosilicate tubing yet, just to see if it would work? Also, I don't think you need to go through the trouble of making hydrogen for this.

For simple (and small-scale) metal oxide reductions, I've used a 2 foot long borosilicate tube that is bent into an "L" shape a few inches from one end. The tube is mounted at a slight angle in a stand, so that some powder can be placed into the long end of the tube without it sliding down by itself. The bent end of the tube faces upward. This gives a low spot at the bottom of the "L", and here is placed a few ml of alcohol.

Any kind of inert gas can be bubbled through this; I've used nitrogen before. It evaporates some alcohol and carries the vapor over the oxide to be reduced. A propane torch can be used to heat the powder. Copper oxide is very simple to reduce this way. You only need 200-300°C to make it work. Higher temperatures will readily cause the copper powder to sinter together.

I've never tried alcohol for reducing iron oxide. Perhaps there could be some inclusion of carbon into the iron, but otherwise it should reduce it just fine, although at a higher temperature. Keep in mind that hot iron will react with water to produce hydrogen again. The gasses have to be absolutely dry. While iron is being reduced water is a product, and this will have to be continually flushed away to bring the reaction to completion.

[Edited on 9-23-2018 by WGTR]

JScott - 28-9-2018 at 11:57

Sorry, it's been a few days since I checked this post. I'm not getting email notification of the responses, sorry if I was rude.

I watched this video nearly three weeks ago (that got me interested). I can't tell you how frustrated I am that I haven't been able to find it since. It was the observations of the color of the burning hydrogen at the end of the tube I found most interesting. I wanted to explore this some, just to satisfy my own personal curiosity. I love watching the videos, sometimes that's enough, there are times when I just say "I have to do that!" I have no better explanation.

One of the things that fascinates me the most about this hobby are the techniques. I love learning about and performing various laboratory techniques. In this case I am less interested in the reduction of iron and more interested in the flooded gas environment and what can be done there. I've watched copper metal formed from copper compounds in a similar manner. It's the technique, not the end result in this case.

I am fairly sure it was hematite. This is NOT the video, but it is now the only one I can find that's even similar. So, I would love to show the video as a reference to what I am trying to describe, but alas I have lost my way.

On the borosilicate tubing, I guess I just assumed that if the quartz tube got bright orange it would be enough heat to melt normal lab glass. In fact I have not tried this with borosilicate glass.

Oh, and I did price plain jane quartz tubing but it wasn't much cheaper than this 'made to order' (no kidding) tube.

[Edited on 9-28-2018 by JScott]

[Edited on 9-28-2018 by JScott]

[Edited on 9-28-2018 by JScott]

[Edited on 9-28-2018 by JScott]

Wrong tube sent!

JScott - 2-10-2018 at 11:24

Dammit! After all of that I get sent a plain old quartz tube. I COULD SCREAM! There that's better.

UPS will by in the AM to take it back.

Back where I started!