III. - Original Latin works

The tradition of practical alchemy underwent an evolution in clarity with the pseudepigraphical Summa perfectionis of Geber, written in
the late 13th c. [3]. The Summa spends three chapters simply describing
the dimensions of a furnace to heat the aludel. The furnace is cylindrical,
with an ash-box at the lowest level, a fire-box above this, and the hearth
at the highest level. The latter space is partitioned off by a transverse
iron rod driven into opposed walls of the cylinder, intended to support an
aludel (or cucurbit). The oven is ventilated with ten air-holes ; it is unspecified whether these and the doors to the ash - and fire-box have
covers. The aludel, which is made of thick glass, is described in detail
(fig. 3). The lower half is made from a rounded concha (rather like the
« urinal » of medieval physicians) to whose neck Geber attaches a circular zona of glass, thus producing a collar. The upper half of the aludel,
which is one span long, fits over the mouth of the concha and rests within
the collar, which is fixed at the bottom : in this way a sealed joint is made.
The conical upper end of the aludel is pierced ; this allows the alchemist
to insert some lint or cotton during sublimation : if powder collects on it,
the process is not finished. The aludel also appears in another work
ascribed to Geber, the L. Fornacum  [4], along with separate furnaces for
calcining, distilling (with a balneum mariae, a water bath), distilling per
descensum (i.e. reduction by means of a descensory like the būt-bar-būt
of Rhases), fusing, dissolving, and fixing (the conversion of a volatile reagent to a non-volatile compound). The cylindrical distillatory and dissolutory furnaces have separate fire-boxes and hearths ; they are variants
of the sublimatory furnace described above. The calcinatory and fusory
ovens, however, are simple shaft furnaces, where the crucibles or cupels
are set directly on the burning fuel. The fixatory furnace has a removable
hearth set in an open shaft : hence it is a hybrid between the sublimatory
and calcinatory types. The L. fornacum specifies that the calcinatory
(and thus fixatory) oven should be rectangular- four feet long, three feet
wide, and one half foot thick. The furnaces in general are made of clay,
molded into sections which then form the component parts of the furnace.

Geber also departs from the Rhases tradition by incorporating
assaying techniques into the Summa. Because these processes required a certain amount of specialized apparatus, it will be useful to describe them. As listed in the Summa perfectionis , they are
cementation, cupellation, firing to the point of glowing, fusion, exposure
to « the vapors of sharp things » (i.e. distilled vinegar and other vegetal
acids), extinction (quenching), immersion of the hot metals in burning
sulfur, the repetition of calcination (in modern parlance « oxidation »)
and reduction, and attempted amalgamation of the metal to be tested
with mercury. It is important to note that the Arabic Kitāb al-Asrār of
Rhases mentions only color as a means of testing the respective metals’
purity (Ruska, 1937). The process of cementation, in which a laminated
or filed metal was placed in a crucible with a variant mixture of vitriol (usually copper or iron sulfate), saltpeter (potassium nitrate), sal ammoniac
(ammonium chloride), table salt, and/or brick dust, then heated at high
temperature, caused the penetration of mineral acids in the form of vapor ; these could be selected to decompose a specific metal while not attacking another. While cementation was known from antiquity both as an
assaying technique and as a means of producing metal compounds for
various applications, one can find many examples of the latter use in the
K. al-Asrār and cognate texts, but none of the former. Only with the Summa perfectionis do we find a systematic description of cementation as
one component in a battery of tests designed to ascertain the success
of transmutation. The same may be said of the ancient technique known
as cupellation, in which a porous cupel exposed to high heat is used to
separate the base metals from gold and silver ; when lead oxide (whose
presence in the alloy to be tested is insured by the addition of metallic
lead, followed by blasting) is formed, it sinks into the walls of the cupel,
carrying other impurities with it. The production of cupels is carefully described in the Summa perfectionis : the author says to sift cinders, calces, or burnt animal bones, or a mixture of all three. These are
then made into a kind of dough, with the addition of water, and that is
shaped into the form of a small pot, whose base is sprinkled with
powdered glass. When the cupels are dry, the metal to be tested is
placed therein, and a fire of coals built upon it, whereupon the test may
proceed. Although Geber does not take the step of quantifying this test,
not even mentioning the analytical balance, his attempts nonetheless
exhibit an incalculable superiority over the color tests of Rhases.

[1 This Liber de investigatione perfectionis magisterii is not the well-known work bearing the
same name, also attributed to Jābir ibn Hayyān (or « Geber » in Latin), and having the incipit « Investigatione(m) hujus nobilis (sime) scientie ex continua ... (TK 776). The latter
text has been printed many times, beginning with the incunabulum version of the Rome
printer Eucharius Silber (s.d. et l.) ; the former exists in manuscript only, though some parts
thereof are excerpted in Ruska (1935a) = [198-237).

[2 My rendition of Rhases’s notes on apparatus is derived entirely from Ruska (1935a) = [198-202).

[3 Gebri ... Summa perfectionis magisterii in sua natura ... , in Manget, J. J., Bibliotheca chemica
, Genevae, 1702, vol. l. This is a reprint with slight variations of the
edition published by Marcellus Silber, and edited by Fausto Sabeo et al., between 1523
and 1527 in Rome. I am presently working on a critical edition of the Summa, but until this
task is accomplished, the reader may be advised to rely on the Sabeo edition and its reprints over the other available versions.

[4 The Liber fornacum, or Liber de fornacibus construendis has only been edited once, as is
also the case with the Liber de inventione perfectionis attributed to Geber. These works
were edited by a pseudonymous « Chrysogonus Polydorus »,and first printed in the ln hoc
volumine de alchemia continentur haec
... , (Nuremberg, 1541), printed by Johannes Petreius - the printer of Copernicus’s De revolutionibus orbium caelestium. Because of the
extreme rarity of this edition and its reprints, I have been forced to use a modern German
translation - Ernst Darmstaedter, Die Alchemie des Geber (Berlin, 1922). The L. fornacum
occupies pp. 114-125 of this version.

[5 The L. fornacum (Darmstaedter, op. cit., 116) calls the fixatory furnace an athanor. If the
L. fornacum is really by the author of the 13th c. Summa perfectionis, we may then see an
early, transitional usage of the term « athanor, we may then see an
early, transitional usage of the term « athanor » here, which is similar to the Arabic tannūr
in that it relates to a high temperature oven. By the 14th c., however, such texts as the
L. de multiplicatione and the L. lucis had restricted the term « athanor » to the low temperature version of the domed furnace.

[6 Archives de l’Administration des Mines et fonds Warocqué (Musée de Mariemont).

[7 Une fois pour toutes, signalons que nous utilisons le terme « histoire des sciences » pour
faire court. Nous préfèrerions le terme, plus adéquat pour désigner notre discipline : « histoire et philosophie de la science et de la technologie ». Il y a encore des historiens qui ne
savent pas que l’histoire ne trouve la justification de son labeur érudit que si elle débouche
sur les problèmes éternels de la philosophie (l’histoire n’est-elle pas encore, pour certains, un genre littéraire ?). Et il y a encore des historiens des sciences qui ne savent pas
que l’étude de l’évolution de la science est impossible sans prendre en compte l’évolution
technologique ...

[8 Il existe un establishment scientifique et industriel comme il existe un establishment littéraire et culturel. La culture, en effet, est aux lettres ce que l’industrie est à la science,
à la fois source et réceptacle. L’écrivain produit des idées qui seront transposées, modulées et diffusées par la culture, comme le scientifique découvre des faits qui alimenteront
l’innovation technologique, moteur de l’industrie. L’ingénieur industriel transpose les
connaissances scientifiques dans le monde de la production en grandes séries, comme
le cinéaste, le journaliste et le réalisateur TV, véritables ingénieurs culturels, transposent
la création littéraire dans le monde de l’imaginaire quotidien, celui du chaud biznesse et
des masse-médiats.

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