What is the chemical formula for Gold Chloride?

[christian_rice]

Am I looking for AuCl or AuCl3? I need to submit exacting requirements to my “sponsor”.

I know I can get the stuff from Photographer’s Formulary and other places, but I’m currently looking at Alfa Assar’s website as a reference…

http://www.alfa.com/en/gp140w.pgm

Not that I’ll end up buying it there, but it does raise a question as to what I’m actually using.

[christian_rice]

Nevermind

AuCl3 pops up in the dagforum. My bad.

[newone2010]

I think it is be called Chloroauric acid hydrated too.It’s HAuCl4.That is what I use.

[christian_rice]

Thanks, Li. That is a different formulation, though I do see HAuCl4 popping up in searches on gilding, as well, so the learning continues each day.

A Wikipedia search on Gold_chloride details the various forms, and does indicate HAuCl4 decomposes to HCl + AuCl3 with heat. And mixed with sodium thiosulphate, I suppose the elemental gold becomes available.

So it seems there’s a number of ways to go. I guess the important part is to give the gold an opportunity to become free when heated. All of which makes me want to go sign up for some chemistry classes at the local college…

“If auric chloride AuCl3 be mixed with a solution of sodium thiosulphate then the gold passes into a colourless solution which deposits colourless crystals containing a double thiosulphate of gold and sodium which are easily soluble in water but are precipitated by alcohol…This salt which is known as Fordos and Giles’s [sic] salt is used in medicine and photography.” — The principles of chemistry, Volume 2, Dmitry Ivanovich Mendeleyev

Also, from http://www.ncbi.nlm.nih.gov/pubmed/11625558 :

[From photography to chrysotherapy: Fordos and Gelis salt].

Devaux G.

Abstract

In 1840, the French physicist Hippolyte Fizeau (1819-1896) proposed an auric chloride and sodium thiosulfate-based reagent to fix daguerreotypes. In 1843, two French pharmacists, Mathurin-Joseph Fordos (1816-1878) and Amedee Gelis (1815-1882), isolated its main ingredient in crystalline form and analysed it as a sodium aurothiosulfate. They recommended the use of an aqueous solution of this product to fix photographic negatives. In this way, the deterioration by sulfuration that negatives underwent with Fizeau’s solution could be avoided. Fordos and Gelis salt came back in the news in 1924 when Prof. Holger Christian Mollgaard (1885-1973) from Copenhagen suggested it under the term Sanocrysine for use in tuberculosis.

(it goes downhill from there, a la “That’s a great idea, Sir Bedivere!” said the king, “This new learning intrigues me. Tell me again how a sheep’s bladders can prevent earthquakes.”)

[newone2010]

The Aucl3 will combine withe the H20 in the air,and turn to HAucl4.If you want to show the H2O clearly in the molecular formula,that will be AuCl3·HCl·4H2O.You do not need to heat HAuCl4(or we can say it AuCl3·HCl·4H2O),just dissolve it into water.

[christian_rice]

So much for Wikipedia…ok, I admit I trust it too much to cover for my ignorance of chemistry. So why do we use heat in the gilding process?

[newone2010]

In the gilding process,I think the gold atoms will escape from the solution by heating,and cover on the surface of the plate.

PS: My English is too bad,so I can not describe what I think clearly.Hope you can understand

[christian_rice]

From everything I’ve read that you’ve posted, I think your English is quite functional.

[Bakody]

What I found is this: HAuCl4.3H2O

So, will this work as well?

http://daginhun.blogspot.com/
 http://www.facebook.com/DagerrotipiaDaguerreotype

[Author]

Posts