9 replies to this topic

[lord_dranack]

The other day I was talking to my chemistry teacher about pyrotechnics, and he mentioned a deminstration he used to do a long time ago. It was called "Pharaoh's serpants" and involved making mercury nitrate from the metal and acid, then reacting with potassium thiocyanate to give mercury thiocyanate, which was dried and placed in a paper funnel then lit, producing snake-like trails of ash. I can't quite remember the exact method, but I think this was about what he said.

Does anyone know if this was ever used in fireworks in the past? I assume it couldn't be used now for health and safety reasons (thats why I put it under nostalgia not pyro)

[BigG]

The burning of mercury salts were responsible for numerous effects – and I can only wish that chemistry teachers will be kind enough to demonstrate the extraordinary qualities of mercury under fire. Mercury was used extensively in the past in fireworks and is still used for speciality fireworks today – mainly “calomel” (Mercurous Chloride) which is an excellent chlorine donor and shockingly enough – not poisonous. Lancaster even gives one of these formulas in his book, and Kentish/Weingrat use it for many of their formulas.

Overall, the price of mercury salts, together with their poisonous characterises is the reason those are not longer in use. Please note that if anyone want to use Mercurous Chloride (HgCl) for chlorine donation they are more then welcome to do so – however, this is not the same as Mercuric chloride (HgCl2) – which is extremely poisonous.

Hope this helps - BigG

[lord_dranack]

Thanks!
The smoke produced with HgCl is likely to be poisonous, but for me HgCl is much, much easier to get than most other chlorine donors.

[crazyjim]

Well, You can see a video of it right here!

http://www.webelemen...ext/Hg/key.html

The lighting is not so good, but you get the gist of what happens.

-Jim

[BigG]

After reading an excellent Spanish article last night “Sparks intensity – Titanium VS it’s alloys” – I decided to look at my library for your serpants. I eliminated Simazu right away – the Japanese will be more likely to call the thing “Harmony with the Chi-tu snakes” or something like that. Davis and Weingrat write about snakes and serpents – but different one then the one the lord described. Then I found it – Lancester, 3rd addition, page 308. Invented in the beginning of the 18th century – and almost killed a royal at 1865… but Lancaster describe it is “less exciting” then other snakes/serpents.

At the same opportunity, I looked up that star formula I mentioned above. I will post it later under an appropriate forum.

Crazyjim - good link

[andy]

Taken from Weingart "To prepare, make a concentrated solution of Mercuric Chloride and add little by little a solution of Potassium Sulphocyanide, stiring constantly.
A greyish precipitate will be formed and when the last drop of sulphocyanide added no longer produces cloudiness permit the mixture to settle"

After that he goes on to tell you to filter it out, wash it and grind the precipitate to a fine powder before adding gum arabic solution and forming into little cones.

Just added this for interest sake and don't suggest you try it at home kids.

[BigG]

Taken from Weingart "To prepare, make a concentrated solution of Mercuric Chloride and add little by little a solution of Potassium Sulphocyanide, stiring constantly.
A greyish precipitate will be formed and when the last drop of sulphocyanide added no longer produces cloudiness permit the mixture to settle"

After that he goes on to tell you to filter it out, wash it and grind the precipitate to a fine powder before adding gum arabic solution and forming into little cones.

Just added this for interest sake and don't suggest you try it at home kids.

Not even funny.

Please ? While the chemicals in question are not highly poisonous, I find it hard to believe that most members understand the chemical reaction involved here. It does become very dangerous if you use certain solvents on this mixtures etc.

Let?s settle for this amount of information and that?s it.

[The Alchemist]

I think that really it is best to keep away from mercury compounds unless you have a through knowledge of inorganic chemistry and a strong grounding in the practical application of chemical practice. And a suitable lab conforming to OSH regulations for the handling of toxic substances.
Even with all these conditions in place several years after working with this compound on two occasions, I recorded very high levels of mercury in my hair. This had resulted from the skin absorbtion of mercury. At that stage I stopped using mercury salts in my compositions and have never since!
Regards
Ray
The Alchemist

Edited by The Alchemist, 28 April 2004 - 10:28 PM.

[Creepin_pyro]

Please note that if anyone want to use Mercurous Chloride (HgCl) for chlorine donation they are more then welcome to do so ? however, this is not the same as Mercuric chloride (HgCl2) ? which is extremely poisonous.

I'm confused. Comparing the Msds's on Mercurous/Mercuric Chloride.

Mercurous Chloride Synonyms: Calomel; Calogreen; Mercury Monochloride; Mercury Chloride

Health Rating: 3 - Severe (Poison)
Flammability Rating: 0 - None
Reactivity Rating: 0 - None
Contact Rating: 3 - Severe (Life)

Mercuric Chloride Synonyms: Mercury bichloride; corrosive sublimate; mercury (II) chloride; mercury perchloride

Health Rating: 4 - Extreme (Poison)
Flammability Rating: 0 - None
Reactivity Rating: 1 - Slight
Contact Rating: 3 - Severe (Life)

It seems the Mercuric Chloride is one notch higher on the poison scale, both substances being highly toxic. I take it one can't be used in the others place.

[lord_dranack]

The reason mercurous chloride is considered less toxic is because it is very insoluble wheras the mercuric chloride will dissolve and give mercury ions.
The mercurous chloride does have some toxic effect, as in the body some mercury ions will be liberated from it.