Pyrophorus holmbergs and others

[jrayj]

Okay, couldn't find anything on this using the search engine. I am interested in making a small amount of pyrophoric material. I was going to use this method: "An artificial product, which takes fire upon exposure to the air, and hence called air-tinder. It is prepared from alum by the addition of various inflammable substances. The simplest mode of preparing it is to mix three parts of alum with one of wheat flour, and calcine them in a phial or mattrass, until the blue flame disappears, then keep it in the same phial till cold, well stopped with a good cork. In this powder be exposed to the atmosphere, the sulphuret attracts moisture from the air, and generates sufficient heat to.kindle the carbonaceous matter mingled with it.". Will this work because I have my doubts. Also, what roll does the alum play? Does it just act as a divider or does it take place in the reaction? I there even a reaction going on besides the burning of wheat flour? But above all would this even work? It just seems to easy to work in my opinion.

[hermanntrude]

I wouldnt advise trying to reproduce an experiment which appears to be several hundred years unless you can find a description a little less outdated. or at least a translation into modern english. I'm not sure about some of the words there and I am sure that in the days when this experiment was described, safety and harzard reduction wasn't part of the game, which is why so many experimenters blow their own faces off in those days.

[jrayj]

I bought a chemistry book written in the 1920's that had some info about pyrophorus materials in it. The main one discussed was the lead based kind but it also had a small section on holmburg's pyrophorus in it. After playing with google for a while I found that description. I also found this description: 4341. Homberg's Pyrophorus

4341. Homberg's Pyrophorus. Stir equal parts of alum and brown sugar (or 3 parts alum and 1 part wheat flour) in an iron ladle over the fire until dry; then put it into an earthen or coated glass phial, and keep it at a red heat so long as flame is emitted; it must then be carefully stopped up and cooled.

 

4342. Hare's Pyrophorus

4342. Hare's Pyrophorus. Lampblack, 3 parts; burnt alum, 4 parts; carbonate of potash, 8 parts; as above.

 

4343. Gay Lussac's Pyrophorus

4343. Gay Lussac's Pyrophorus. Sulphate of potash, 9 parts; calcined lampblack, 5 parts; as last.

 

4344. Goebel's Pyrophorus

4344. Goebel's Pyrophorus. Heat tartrate of lead red hot in a glass tube, and then hermetically seal it.

 

which seems a little less outdated. Is there a major safety hazard associated with doing this?

[hermanntrude]

the fact is that i'm not sure. A modern procedure would mention the hazards. Also, it'd probably mention the reactions involved which would give more clues as to the safety or lack thereof

[jrayj]

Oh, well thanks, before I go about "blowing my face off" or even putting my face at risk I'm going to see if I can find a more modern procedure. The internet seems fruitless though as these this has almost no use nowadays. I might have to try find a book.

[hermanntrude]

try looking up the individual reactants ("lampblack", "alum" etc) to find out their real chemical names or major components. then you might be able to google to find the reactions they undergo

[UC]

Here's one that should definetly work. I seriously question if those other preparation (except the lead one) would work, or at the very least are probably very very difficult to get to work.

 

Place some dry ferrous oxalate (yellow) in a test tube and plug the top end loosely with glass wool. Heat the ferrous oxalate until gas ceases to be evolved (CO2), leaving a black, magnetic powder. This powder is probably a mix of extremely finely powdered iron and probably a little FeO. The CO2 acts as a shielding gas and the glass wool prevents pressure from building up, but also stops air from flowing into the tube. When the glass wool is removed and the powder poured into air, the bits of iron rapidly react with oxygen and "ignite" (glow strongly). You could seal the tube off as an ampoule if you really wanted. Cobalt and nickel look like other good candidates. Perhaps manganese.

 

Based on the same principles, your lead tartrate will probably work as well, but as iron is more reactive, it will probably be more impressive. (and not toxic)

 

You may also be interested in this. It isn't quite pyrophoric, but rather impressive: http://www.theodoregray.com/PeriodicTable/PopularScience/2005/10/1/index.html

 

Do I even need to mention to be careful with something like that? It should be obvious.

Edited February 2, 2009 by UC

[jrayj]

thanks, I might try the iron oxalate later this week.