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Date: Thu, 11 Jun 1998
From: Joel Tetard

Hello to all,I am looking for information about the use of melting salts
(tartare salt, carbonate potassium, etc.) used as a mean for protecting
molten metals against oxidation and/or sublimation in crucible.

In my opinion, molten salts could be used as a "screen" over molten metals.

I wonder what is the maximum temperature of each salts before they are
destroyed by heat.

Any information about these matter ?

Many thanks in advance.

Regards

Joel

From: Jean-Pierre Valjean
Date: Thu, 11 Jun 1998

Monsieur Tetard,

Votre question est quelque peu specialisee et j'ai peu de temps
aujourd'hui pour assurer une traduction coherente. Jean-Pierre, mon
frere bilingue, est en voyage au Canada. Mon anglais me suffit pour
lire. J'espere que vous etes francophone comme votre non semble
indiquer. Premierement, la meilleure facon d'eviter l'oxidation dans le
creuset est le couvercle du creuset. Le role des sels que vous avez
mentionne est
l'acceleration et l'homogenisation de la fonte. Le tarte cru, contenant
du carbone qui se libere lors du rajout a un creuset chauffe a environ
800 C , peut contribuer a transformer les sufates et sulfures en metaux
purs car le carbone se combine bien au soufre. Il y a aussi tout le
sujet du travail a la chaleur oxidante et a la chaleur reductive que
vous pouvez trouver dans les livres de metallurgie. Il serait
probablement plus facile de repondre a votre question si vous pouuriez
etre specifique a propos du metal.

Jean-Paul (frere de Jean-Pierre) Valjean

From: Anthony House
Date: Thu, 11 Jun 1998

Joel,
The URL

http://spruce.lib.utexas.edu/thermodex/

lists a search engine for texts that may answer this and many
more questions related.

Hope it helps....

Anthony

From: Anthony House
Date: Thu, 11 Jun 1998

Dear Joel,

It can also be noted that in the making of Bhasma's from metals that are
melted and then poured into buttermilk, for instance zinc, the zinc thus
poured into the organic acid of the buttermilk becomes brittle and easily
broken up. We are making in this way organic rings around the metallic
atoms, reanimating the dead (melted metal). This is an example of a
protective coating that the metal receives from organic acids in the milk. A
bhasma is a powder form of medicine used regularly in Ayurvedic medicine.

Anthony

Date: Fri, 12 Jun 1998
From: Rubea Viridis

Mister House,

The rings found on zinc bhasmas are formed after the process of melting
and pouring into buttermilk; the following steps include :

1) putting a dried herb powder into the melted zinc to get a black powder and
2) mixing with a fresh herb and
3) calcining in a oven.

These processes stabilize the bhasma.

Rubea Viridis

Date: Fri, 12 Jun 1998
From: Jerome E. Tamul

Joel Tetard wrote:
>I am looking for information about the use of melting salts
> (tartare salt, carbonate potassium, etc.) used as a mean for protecting
> molten metals against oxidation and/or sublimation in crucible.

What you want is a flux. The purpose of a flux is to protect a molten
metal from oxidation and/or to remove impurities. There are many
different fluxes and their application depends on the type of metal,
what impurities are present, the temperature, and the reactivity of
the flux with the metal.

Potassium carbonate may or may not be appropriate as a flux. Potassium
carbonate melts at 891C, and vaporizes unchanged at white heat.
Potassium tartrate decomposes at 200-220C forming potassium carbonate,
carbon, and destructive distillation products.

Jerome

Date: Fri, 12 Jun 1998
From: Johann Plattner

Dear Joel,

Melting salts, for instance potash or soda, are used in order to remove
arsenic from the regulus of antimony. The reaction in the crucible is:

3nK2CO3 + 2,5 O2 + 2 As ---> 2 K3AsO4 + 3 CO2.

Later, the orthoarsenate is swimming upon the melted antimony
and could be removed.
The melting point of the orthoarsenate is 1310°C.

K2CO3: melting point: 891°C, density: 2,428
Na2CO3: melting point: 851°C, density: 2,532

Both carbonates will decompose if heated above its melting points.

K2CO3 ---> K2O + CO2, (K2O is decomposing at 350°C)
Na2CO3 ---> Na2O + CO2, (Na2O is sublimating at 1275°C)

Best wishes
Johann Plattner

Date: Mon, 15 Jun 1998
From: Joel Tetard

Many thanks to Jean-Pierre, Anthony, Jerome and other
friends for their helpful information concerning the use of salts as flux.

I did not give the reason why I am looking for information about this
subject. Recently I read (one more time again. "Lege, lege, relege ..." !)
the excellent Bernard Husson's "Anthology de l'Alchimie" (Editions
Pierre Belfond, Paris, 1971).

I quoted some interesting remarks concerning the question of the
"activation" of the Subject with the Spiritus Mundi by means of dew for the
humid path, and by molten salt(s) for the dry path.
I do apologize for giving these texts in French.

I'll try translate them later but this text is rather difficult : I'm
afraid of being unprecise for my English vocabulary is too "basic"
for this purpose. Help will be welcome !.

"La technique alchimique � laquelle font allusion, sous des modalit�s
vari�es, les auteurs choisis dans notre anthologie, apparait � pr�sent,
nous l'esp�rons du moins, assez nettement au lecteur : c'est, dans la
voie humide ou longue, un proc�d� combinant celui de Beker aux
op�rations spagyriques sur l'antimoine dans lequel le myst�rieux
sel isol� par le spagyriste se concentre directement au sein des
substances min�rales et m�talliques dont il va �vertuer les pincipes
actifs ou "semences".

"Quant � la voie s�che, on se reportera � notre note sur les flux salins
et vitreux, ou verres graduatoires, concernant l'histoire de l'alchimiste
inconnu de Halle.
" elle marque la distinction entre le spagyriste et l'alchimiste adepte qui
utilise directement, au sein d'un v�hicule salin fondu, � des temp�ratures
exigeant l'emploi constant et exclusif du creuset, la lumi�re de nature,
que cet excipient permet de concentrer en faisant appel au myst�rieux
pouvoir du feu alchimique que, par analogie, nous croyons pouvoir
rapprocher de tout �tat ionis� de la mati�re."

Now, this is the text of the footnote concerning saline flux on page 15 :

"les m�tallurgistes allemands et autrichiens du XVII et XVIIIeme si�cles
appelaient "glass", verre", les flux ou fondants, g�n�ralement � base
de plomb, de borates et de silicates, destin�s � prot�ger de l'oxydation
et de l'�vaporation les minerais fondus au creusets. Certains de ces flux
(en allemand fluss, � raprocher cabalistiquement de Vliess et du latin
Vellus, qui �voque l'Aureum Vellus, la toison d'or, la couverture aurifiante)
� la composition �videmment tenue secr�te, �taient susceptible de
communiquer � l'argent, au bout d'une tr�s logue fusion, un certain
enrichissement en or, appel� graduation ou gradation. Quantit� de
chimistes et de m�tallurgistes du temps en font �tat dans leurs ouvrages,
mais ils insistent tous sur l'obstacle quasi-infranchissables que constitue,
pour l'utilisation de ces proc�d�s, le fait qu'au bout de quelques heures
de fusion les meilleurs creusets sont perc�s ou tout du moins p�n�tr�s
et rendus poreux � l'�gard du fondant qu'ils laissent finalement �chapper".

Best wishes.

Joel