Aqua fortis

Nitric acid, or aqua fortis as it was called in medieval times, has been known and used by mankind for centuries. At first, it was produced by heating a mixture of sodium nitrate (Chile saltpeter) and sulfuric acid. The product obtained was sodium hydrogen sulfate, and the nitric acid vapors escaping during this process were condensed ... 

X.tze,/. corrosion etching cauterization etching liquid, esp. aqua fortis (Calico) discharge. 

The alchemists of the Middle Ages were no strangers to acids. In fact, aqua fortis, which literally means "strong water," is basically nitric acid. Alchemists used aqua fortis to dissolve certain metals. Specifically, they used it to separate silver (which would dissolve in aqua fortis) from gold (which would not). 

Synonyms Aqua fortis azotic acid hydrogen nitrate... 

Vitriol fire aqua fortis aqua regis Amalgam Alembic. 

Aqua Regia. Geber described the preparation of nitric acid (aqua fortis) in his De inventione veritatis, and added that, if one adds sal ammoniac to this acid it becomes a more powerful solvent (5, 16). Raymond Lully (Raimundo Lulio) and Albert the Great (St. Albert) prepared it in the same way. By the time the writings attributed to Basil Valentine were published, hydrochloric acid (acid of salt) was known, this work describes the preparation of aqua regia by mixing three parts of hydrochloric acid with one part of nitric acid (16,17). J. R. Glauber prepared it from common salt and nitric acid and from saltpeter and hydrochloric acid (18). 

In another paper of 1713, Lemery le cadet is concerned to find out why saltpeter enhances the inflammation of combustibles, and other salts do not. When saltpeter and vitriol are heated together in a crucible to make aqua fortis, the saltpeter is found deprived of its acids, which are evolved, while those of the vitriol remain at the bottom of the crucible with the matrix of the saltpeter. Lemery here is using matrix almost as we would use base. It is also clear that he has a fairly well developed idea of the pattern of exchange of partners, or what later is called affinity. Later, Lemery explains why alum and vitriol do not cause an increase in the inflammation of a combustible oil ... 

Wollaston s method, of which the preceding is a modification, is the most perfect, and that best calculated to yield a pure metal,. Vauquelin struck upon the same, but in its details that of the former is the most complete. For tire preparation of the pure metal, the platiniferous grains arc treated with aqua regia and chloride of ammonium, as in the preceding case ouly, to prevent the solution of the iridium it is necessary to dilute the acids, so that it will remain in the residue. It is well to reduce the strength of the- hydrochloric acid with on equal quantity of water, and also that the aqua-fortis and muriatic acid bo quite pure. - Wollaston has indicated that a quantity of ydrochlorio acid, equivalent to one hundred and fifty of dry acid, and as much nitric acid as will contein forty parts, Is sufficient for the solution of a hundred parts of the platiniferous matter hut as it is best to have an excess of the ore, one hundred and twenty parts of the latter should be employed. The action of the compound acid should... 

Dissolve in aqua fortis take the resulting water and pour into bad [impure ] water which is warm or salty, and the silver settles as a powder. Let it settle well, pour... 

The formation of silver amalgam is described by dissolving silver in aqua fortis and then ... 

The separation of the elements from metals is a process in which you should provide yourself with good apparatus, and with experienced manipulation and workmanship. First make an aqua fortis thus take of alum, vitriol, sal-nitri, equal parts, distil to a strong aqua fortis, return that to the residue and distil a second time in a glass flask. Dissolve in this silver and afterwards dissolve in it sal ammoniac. After this is done take the metal in thin plates and dissolve it in the water. When that has taken place separate it in the water bath (balneo mar is), pour it over again until an oil is found at the bottom from gold almost brown, from silver almost bluish, from iron red to almost black, from mercury quite white, from lead lead-colored, from copper quite green, from tin, yellow. 

It will be noted that in the separation of gold from silver the aqua fortis used must be free from hydrochloric acid, while in the separation of silver from copper the aqua fortis must have contained hydrochloric acid to have separated the silver as chloride. Paracelsus does not discriminate however. So also the description of the foul waters used... 

In the fourth book he describes the preparation of and use of aqua fortis in parting, and processes of cementation by sulphur, or by antimony. 

Book Ten deals with the making of the mineral acids used in assaying and in parting operations. Aqua valens is the term which Agricola employs indiscriminately for the acids or mixtures of acids, ignoring the terms aqua fortis or aqua regia then already introduced by previous writers. His description of the materials used for preparation would indicate that a considerable variety of strength and composition of these acids were in use. He describes ten recipes for the materials to be subjected to distillation in the furnace. 

If we assume that Paracelsus here means by Instrument der Scheydung the operation of parting in assaying, a common process in his time and elsewhere described by him, that process consisted in the solution of alloys of silver or gold with other metals by aqua fortis (nitric acid) and the effervescence he refers to would be caused by nitrogen oxides, not hydrogen. 

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