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Aqua Regia

Hello Chemists!

    Total amateur here, please be gentle.  I am a medieval recreationist researching the production of aqua regia during the Middle Ages.  I have the recipe from a manuscript from approximately 1300 CE.  My goal was to produce aqua regia with using a close proximation of the process used in the medieval period.   I am not having a great deal of success because modern sources take me in too many directions.  

   I was hoping that you could help me understand what it chemically going on in this process, perhaps that will help.  Modern aqua regia is 1:3 HNO3 and HCL.  Got it.  

   Our medieval formula is 1 pound of CuSO4, 1/2 pound of KNO3, 1/4 pound of KAL(SO4), and 1/4 pound of NH4Cl.   They put this in a medieval alembic and distilled aqua regia.  Somehow.   

   My uneducated guess is that the sulfates are somehow becoming sulfuric acids which combine with the potassium nitrate to produce nitric acid.  The ammonium chloride provides the HCL? 

Can anyone, in layman's terms, help me understand how this process is happening.  In terms of trying to recreate it, does anyone have any suggestions.  So far, combining the materials in a much smaller amount, but in a consistent ratio, and running them through basic distillation is not working. 

Thanks for humoring my very odd question, and thanks in advance for the assist, 


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Re: Aqua Regia

"In fact, the cited recipe leads to two potent solvents: the beginning describes the preparation of nitric acid, whereas the subsequent addition of sal ammoniac turns it into aqua regia, a mixture of hydrochloric and nitric acid, which indeed dissolves gold. The expression “red [color ?] of alembic” suggests that a high temperature is necessary"



SOME NOTES On THE EARLY HISTORY Of nItrIc acId: 1300 – 1700 Vladimír Karpenko, Charles University, Czech Republic


BULLETIN FOR THE HISTORY OF CHEMISTRY Division of the History of Chemistry of the American Chemical Society VOLUME 34 Number 2 2009


I would make the nitric acid first, distill it, then add the other substance to make aqua regia. the full recipe from the above mentioned article is this:


"The recipe in L. de inventione veritatis is as follows (9):

In the first place I will speake about our solvent [aqua nostra dissolutiva] that I had mentioned in our ‘Summa,’ there, where I had spoken about dissolving with strong liquids. First take one pound of vitriol [CuSO4.5H2O], one half of a pound of saltpeter [KNO3], and one quarter of a pound of alum [KAl(SO4)2.12 H2O]. Prepare this liquid with red [color ?] of alembic, because it has a high solvent action. Use it, as was given in the preceding chapters. It will be yet much stronger if thou dissolveth a quarter of a pound of sal ammoniac [NH4Cl] in it. This liquid then dissolves gold, sulfur, and silver"


If you just try to throw all of the things in a pot then you will get side reactions and not the end product. You need to follow the steps exactly for chemical reactions. 

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