IV. Seventeenth-Century Experiments with Glass Drops: Robert Hooke on glass drops

In the previous posts, I have introduced the problem of glass drops in the seventeenth-century natural philosophy, which I have further discussed in the case of Jacques Rohault’s Cartesian experimentalism and other Cartesian explanations provided by Henricus Regius and Nicolas-Joseph Poisson.

In the final post on this topic, I would like to refer to the explanation provided by an experimental philosopher par excellence, Robert Hooke (1635-1703).

Some of the earliest investigations of the drops took place in the Royal Society (see Brodsley, Laurel, Charles Frank, and John Steeds. 1986. “Prince Rupert’s Drops.” Notes and Records of the Royal Society of London 41 (1) (October): 1–26). Hooke was one of its most distinguished members and witnessed these inquiries from the very beginning (see Birch, Thomas. 1756. History of the Royal Society. Vol. I. London: A. Millar). After an initial report signed by Robert Moray in 1661, Hooke published his own observations in the celebrated Micrographia of 1665. He applies jointly direct observation, hypothetical thinking, and experiment in order to formulate an explanation “Of some Phenomena of Glass drops,” as it is said in the title of his seventh observation. As expected, glass drops and fragments of drops are examined through the microscope. Yet, Hooke notes the difficulties of his inquiry: “I could not find, either with my naked Eye, or a Microscope, that any of the broken pieces were of a regular figure, nor any one like another, but for the most part those that flaw’d off in large pieces were prettily branched” (p. 33). Trying to find the imperfection of glass, sets Hooke on a quest of successive trials, such as grinding the object in different parts and observe if there are new effects or immersing glass drops in various substances (e.g., Icthyocolla). Like in the prior cases of Rohault and Regius, Hooke complements his text with an illustration (see Fig. X at the bottom of this image):

Robert Hooke, Micrographia (1665).

The object is not only investigated empirically with various instruments, but the ‘conjectures’ formed in this process are further examined through analogy and transduction, which ports theoretical elements into Hooke’s analysis. Moreover, descending into the invisible structures of matter, forces him to leave the eye and the microscope and frame his explanation on top of other prior considerations about heat, fluidity, and matter in general. He concludes by ascribing the cause to the arrangement of particles of glass, which are gathered into a springy tension inside the drop.

It is not the place in this blog-post to go into the details of Hooke’s explanation of the phenomena produced by glass drops, but it is worth noticing that his experimental methodology overlaps with what I have presented in the post dedicated to Rohault. Theory and experimentation work together in finding the explanation, which, ultimately reduces to a mechanical model of the accepted theory of matter. These four cases of seventeenth-century natural philosophers interested in the study of glass drops make wonderful examples of how “new scientific objects” are discussed and explored with new methodological tools. I shall investigate this problem into a forthcoming article.

III. Seventeenth-Century Experiments with Glass Drops: Henricus Regius and Nicolas Poisson on glass drops

Rohault was not the only Cartesian natural philosopher interested into the mysteries of glass drops. Others have started to examine the object and to produce their own explanations. In this post, I shall refer to the cases of Henricus Regius and Nicolas Poisson.

Regius (1598-1679) was a former friend of Descartes, who eventually felt into disgrace in the 1640s as a result of the disputes stirred at the University of Utrecht (see Verbeek, Theo. 1988. La Querelle d’Utrecht, Paris: Les impressions nouvelles). Descartes’s accusations from the preface letter to the French edition of the Principia philosophiae (1647) are directed to Regius’s new treatise Fundamenta Physices (1646). The accusations and the dispute between the two are beyond the scope of this post. However, it is important to notice the context in which Regius has developed his natural philosophy. In subsequent editions of the Fundamenta, he explored a larger area of the natural realm, introducing a discussion of glass drops in the final part of the Philosophia naturalis (1661, the third edition of the Fundamenta, but not in the second edition from 1654). This part is an eclectic collection of phenomena, curiosities, and experiments, which is in many ways reminiscent of Francis Bacon’s Sylva sylvarum. And, quite surprisingly, Regius adds his own explanation regarding this new object.

Henricus Regius, Philosophia naturalis (1661), p. 516.

It is evident from the very beginning that he is interested in uncovering the cause and it is not very clear whether he performed any experiments with glass drops. Unlike other explanations, Regius is not very concerned with the structure of the drop in its larger part (the area marked with 1-2 in his illustration), but rather with the structure of the tail. He refers to the structure of the object, which he seeks to explain in terms of glass particles and pores. Even if Regius’s explanation is not very elaborate, it still gives the general outlines found in other popular descriptions of the phenomenon.

Almost a decade later, Nicolas-Joseph Poisson (1637-17010) has published his Commentaire ou remarques sur la méthode de René Descartes (1670). Poisson attempts to defend Descartes’s views on method and he does this by taking each of the four rules expressed in the Discours de la méthode, which are correlated with new experiments and discoveries. In his discussion of the second rule –  “La seconde Regle de la Logique de M. Desc. est de diviser ou faire une espece d’anatomie de la difficulté qu’il se propose d’examiner il la regarde d’abord en general, puis distinguant chaque partie, il les demesle les unes d’avec les autres pour les contempler chacune en particulier, & en connoistre la nature & les proprietez.” (see the 1987 reprint of Poisson’s Commentaire, p. 54) – Poisson introduces the explanation of glass drops. Relying mainly on other testimonies, he is concerned with the explanation of this phenomenon, which he eventually achieves. However, what is peculiar to his explanation is that he begins with a list of what is important in his search. Thus, he enumerates: (1) the material condition (only air and glass are contained in the object); (2) the position of glass; (3) cause of the structure (action of fire); (4) how glass interact; (5) the relation between hot and cold with respect to glass; (6) the existence of a so-called ‘motion of liberty’ of the air that is trapped inside the drops (Poisson refers here to the mechanical tradition); (7) the “elastic” virtue of the air (with reference to Boyle); (8) the heavy force of the trapped air, which he claims will burst with great noise, as soon as it is freed. This list is quite strange, because his explanation can easily be reduced to all these eight points. But this can be due to the interplay between a resolutive and constructive procedure, which is traditionally ascribed to Cartesian method.

These two cases of Cartesian philosophers dealing with a new object puzzling early modern philosophers reveals another layer of the relation between theory and experimentation. Both Regius and Poisson seems to rely on observations and reports produces by others. Experiment is not neglected, yet it is not central, because what both of them seek is to produce an explanation, which ultimately rests on the mechanical structure of invisible parts of matter. In the next post, we shall see how a similar explanation emerges in the case of an experimental philosopher, Robert Hooke.


II. Seventeenth-Century Experiments with Glass Drops: Jacques Rohault and his Cartesian experimentalism

In the previous post, I’ve only introduced glass drops as objects of philosophical study in the early modern Europe. I argued that they have become popular in the late 1650s and early 1660s, at the same time with the spread of a more extensive experimental attitude in the investigation of nature. In this post, I shall give a brief account of Jacques Rohault’s empirical investigation of these objects.

Rohault (1618-1672) was one of the leading Cartesian philosophers of his time. He hosted a famous salon in Paris, where he jointly discussed problems of natural philosophy in connection with experiments. Moreover, his book on physics – the Traité de physique (1671) – was quickly adopted as a textbook on natural philosophy in various universities. As I argue in a forthcoming article, much of Rohault’s experimental work has been done in the late 1650s and early 1660s (see Dobre, Mihnea. “Rohault’s Cartesian Physics.” In Cartesian Empiricisms, eds. Dobre, Mihnea and Nyden, Tammy. Springer Studies in History and Philosophy of Science. Springer). Among his experiments, Rohault performed some with “larmes de verre” (see Christiaan Huygens’s report from March 17, 1660: “Rohaut [sic], qui fit l’experience d’une larme de verre” in Huygens, Oeuvres XXII, p. 562).


Jacques Rohault. Traité de physique (1671), p. 173.

For Rohault, glass drops (“larmes de verre”) are wonders of nature, which means that they challenge natural philosophy. Stating the extraordinary character of the object from the very beginning allows him to test the explanatory power of his own natural philosophy. This comes with both a theoretical and experimental dimension. First, Rohault draws the boundaries of his explanation in terms of what is theoretically acceptable; in other words, a general description of how motion works. Then, Rohault performs several observations, showing: (1) the quick cooling of glass; (2) that glass-surface becomes cooler, which he already explains by the fact that it closes its pores; (3) matter inside is still agitated producing both glass powder and larger pores; and finally, (4) the question: why is not breaking?

All sorts of experimental trials accompany the first three steps of this investigation. Rohault applies various operations to the larme de verre (e.g., attempts to break the drop in other points than D or to immerse the object in different substances and observe changes in the properties of the glass), which can be considered variations in the experimental procedure. He concludes his empirical investigations by answering the fourth point from above. Glass drops are difficult to break on point D, because of the arrangement of matter: the inner part of the drop is formed by a mixture of air and glass – with some sort of arch-structures – while the external part is very dense. This is easily explained by the process of fabrication: when melted glass is left to plunge into a flask of cold water, it quickly cools, such that glass particles that are in contact with water will solidify immediately, while the inner parts will continue their motion.

Using jointly the principles of Cartesian natural philosophy and an experimental method, Rohault is forced at this point to delve into the hidden structure of bodies. He appeals to Cartesian theory of matter (body is identical with matter and space; void space is not possible) and mechanical modeling of interacting bodies. Yet, this is done in a similar manner with his contemporaries, the so-called experimental philosophers.

In the next post, I shall discuss the cases of Henricus Regius and Nicolas Poisson. That will conclude my overview of Cartesian natural philosophers dealing with the problem of glass drops.

I. Seventeenth-Century Experiments with Glass Drops: an introduction

One of the new ‘scientific’ objects that captured the attention of the seventeenth-century French and British experimentalists is what they call a ‘glass drop’: the result of dropping a bit of incandescent glass into a bucket of cold water. Peculiar to this object was its solidity, which was contrasted with the very minute fragmentation of glass that was produced when the drop was finally destroyed.

A representation of the glass drop can be observed in the following illustration from Jacques Rohault’s Traité de physique (1671).

Jacques Rohault. Traité de physique (1671), p. 173.

This is the first post of a series discussing some seventeenth-century attempts to explain the properties of glass drops. Considered as one of the most intriguing objects, glass drop became an interesting item of study for many natural philosophers, including Robert Boyle, Jacques Rohault, Henricus Regius or Robert Hooke. As its name suggests, the object was made of glass and its peculiar shape intrigued as much as its apparently contradictory properties. On the one hand, the glass drop was found very difficult to break when it was pressed on the large size of the drop. On the other hand, its tail was very easy to fracture, which produced the blow of the drop with a loud noise.

A modern replica of the phenomena – starting from the production process of the drop and continuing with an exemplification of the two properties described above – is possible to watch online on the website of the Corning Museum of Glass (see http://www.cmog.org/video/prince-ruperts-drop): http://youtu.be/6V2eCFsDkK0.

The glass drop became philosophically interesting only in the seventeenth century. References to its structure and properties appeared almost at the same time in several places of Europe. The drop had also different names: larme de verre, lacryma Batavica, chymical glass, Prince Rupert’s drop, vitrae lacrymae, globuli vitrei, Batavian tears, etc. Its origins are still controversial, but it is commonly held that it came from either German lands or the Dutch provinces. I shall not try in these blog-posts to discuss the origins of this object or to attempt to correct some misconceptions about who has the priority in the philosophical investigation of the drop (an overview of these problems is in Brodsley, Laurel, Charles Frank, and John Steeds. 1986. “Prince Rupert’s Drops.” Notes and Records of the Royal Society of London 41 (1) (October): 1–26.). Rather, by looking at some of the early discussions and explanations of the phenomena produced by glass drops, I would like to suggest that early modern authors were forced to tackle the problem in a manner that included both theoretical and experimental examinations. This makes the glass drop case important for any discussion about the sources of knowledge in early modern philosophy, complicating the traditional divide between Rationalists and Empiricists and shading a new light on other more recent attempts to use actor-category terms, such as experimental and speculative (see the research project on Early Modern Experimental Philosophy at the University of Otago: https://blogs.otago.ac.nz/emxphi/the-project/).

In the next post, I shall discuss Jacques Rohault’s explanation of the phenomena.

The sources of Francis Bacon’s natural history: vexing questions

Francis Bacon was very much immersed in the humanist tradition: he borrowed freely and creatively from many sources. Writing as he did for a cultivated reader, he rarely identified his source by name or explicit references. In many cases, this was just because any cultivated reader would be expected to know that a certain passage is a quote or a special reading of a well known author/paragraph. In other cases, this was a rhetoric strategy destined to select the readers (those being able to perform the ‘recognition’ task were the ‘more advanced’ readers, the ‘true sons of science’).

Today, this way of writing poses numerous problems: we are far less educated than Bacon’s contemporaries. Meanwhile, it would be very important to recognize Bacon’s sources. In some cases, this would be vital for the understanding of what is at stake in Bacon’s text. Such is the case of natural histories where Bacon freely used ancient and modern authors as sources.

Sources in natural histories

As we have discussed in our previous seminar, and as it became clear from Doina’s presentation of Bacon’s ‘borrowings’ from Della Porta, a large part of Sylva Sylvarum is constructed on a solid basis of ‘facts’ borrowed from natural historical sources. Despite the fact that Ellis, Spedding and Rees have all given  some statistics (30-50 % ‘borrowings’) there is still major work to be done on the identification of Bacon’s sources. It involves a considerable amount of historical and archival research. The more philosophical aspect of it  would be to consider, carefully, how Bacon read, borrowed, and handled the borrowings. In what way he constructed his own experiments from an ancient report or from another experiment taken from Della Porta. In what way he reflected upon the material he used (was he really using it as a ‘fact’? was he reflecting critically on it? At what level were his critical reflections? Theoretical? Methodological? Epistemological?).

Our edition of Sylva

The major challenge in the case of our projected edition is the identification of the sources of a text in which almost every second paragraph refers to an ancient and Renaissance source. We won’t be able to identify all of them. However, even beginning to scrap the surface would be useful, because it would provide the starting point for future contextual (and ‘philosophical’) readings and interpretations of Sylva Sylvarum and other natural histories.

Brunschwig’s “vertuose boke of distyllacyon”

One of the first books dedicated to the art of distillation, Liber de arte distilandi, was published in 1500 by a german physisican, the paracelsian Hieronymus Brunschwig (1450 – 1512). In 1512, Brunschwig publishes an extended version of this small treatise, entitled Grosse Distillierbuch. This book is translated in Dutch in 1519 and then in english in 1527 by Lawrence Andrew. The title of the English translation was: „The vertuose boke of distyllacyon of the waters of all maner of herbes, with the fygures of the styllatoryes : fyrst made and compyled by the thyrte yeres study and labour of the moste cnynge and famous master of phisyke, Maister Iherom bruynswyke : and now newly translate out of Duyche into Englysshe, nat only to the synguler helpe and profyte of the surgyens, phisycyens, and pothecaryes, but also of all maner of people, parfytely and in dewe tyme and ordre to lerne to dystyll all maner of herbes, to the profyte, cure, & remedy of all maner dysseases and infirmytees apparant and nat apparant : and ye shall understande that the waters be better than the herbes, as Avicenna testefyeth in his fourth canon saynge that all maner medicynes used with theyr substance, febleth and maketh aged, and weke.” As the title shows, the book was received as a textbook of pharmacology, because an important part of the book is dedicated to medicinal drinks and cures. But we can also read this book as a textbook of the “know-how” of distillation.

Structure of the book:  The first chapter offers a definition of the science of distillation and an emphasis of its usefulness for medicine. Then a large part of the book is dedicated to a detailed and systematic description of the manners of distilling. Brunschwig is careful in providing the „know-how” of the “instrumentarium” and the actual procedures of distillation. This part includes an important number of illustrations depicting the equipment; that is the vessels for distillations, the gluing substance, the furnals. Brunschwig is careful in offering all the necessary details to put into practice the art of distillation: for example, he is very careful in specifying the type of glass needed (venetian, bohemian glass) so that it can “better withstande the hete of the fyre”. The description of the instrument and the entire distillation laboratory is interesting not only because it provides a lot of details, but also because Brunschwig makes interesting considerations about the technological limits of the operation. He attempts to provide an exhaustive list of vessels  used in distillations: retorts, “glasses with two arms called pelicans” used for recirculating procedures, “blind helms” (a glass lyke a gorde torned into another glass without any pipe), “circulatories” (glasses that are “wide above and beneath and narrowe in the middest”, with a tube projecting from the vessel).  Two other aspects are described in detail: the glueing substance of the vessel and how to build the furnaces, so as to control the fire, for example by ventilation (“to every smoke hole ye shall make a…tappe to governe your fyre). Then, the book considers a number of aspects that are important for a correct distillation of specific substances and for the preservation of the new distilled liquor. The last part of the book (and the widest) is dedicated to showing how to distil each type of medicinal plant; thus establishing what type of distilling procedure is appropriate for a given plant, flower or substance (like vingar, spirit of wine, oils, etc.)

Definition of distillation:

„Distilling is none other thinge/ but one is a purifying of the gross from the subtyle/ or the subtyle from the gross/ each separately from other/ to the intent that the corruptyble shall be made incorruptyble/ and to make the materyall imateryall/ and the quick spyryt to be made quicker because it sholde the soner pierce and passé thrugh by the virtue of his great goodness and strengthe that there is in and sunke and hydde for the concyvyng of the helthfull operacyon in the body of man..” — thus, distillation covers all procedures of separation of bodies and their condensation in liquids.

Brunschwig parallels alchemy with distillation since via distillation the good, medicinal part of a substance is separated from its more impure and harmful part.



Ways and manners of distillation.


Provided the definition, Brunschwig identifies 2 major ways of distilling: with and without fire, or otherwise said with and without cost. Each of these 2 ways, includes several procedures of distillation. These procedures are different experimental set-ups which will be used according to their appropriateness for given substances.  To clarify a substance, heating and circulating are crucial. As such, he is very careful in suggesting ways to control the fire for the distillations with cost either in the construction of furnals, the placement of the stillatories in the furnals.

Distillation without fire: Sources of heat: sun, putrefaction, fermentation

  1. Filtrum distillacio – (distillation with silt).
  2. Folis distillacionem – a form of solar distillation that uses a brinaile (a glass “almost as wide above as beneath”). The brinaile is filled with flowers, a layer of sticks covers its mouth, then it is turned upsidedown and inserted into another glass, glued  and then let in the sun
  3. Per panis distillacionem (fermenting dough)  – a small glass is filled with flowers or herbs and then put in the oven inside the baking bread
  4. Finnie equi distillacionem (distillation in horse dung) –  this is a procedure of doble distillation (first with vessels called cucumber and then in another vessel called pelican). The pelican vessel is useful for recirculating distilaltes, what Brunschwig calls the rectification of waters.
  5. Formyre distillacionem- distillation in anthills (same principle as 4, but the set-up is different).

This procedure can be slow as in the case of the distillations with horse dung or anthills, where the distillation might last from 2 weeks up to months, but also faster forms of distillation as panis distillation.

Distillation with fire:

  1. Balneo marie : “The glass shall be set in warm water, which water shall be in a copper kettle. Take a glass named curcubit, fill the two parts of the same glass with juice herbs, flowers, leaves, fruits or whatsoever it be chopped small, and set the glass upon a ring of lead. Make a bond of cloth three fingers broad about the upper part of the glass. About the same band make four small rings of cloth having four bands coming down to the four rings that be fast on the leaden ring and bind then fast each to the other. Then let the glass with the lid in the water and standing upright and is sure from falling on the one side or the other through the weight of the lid. Then set the alembic or glass and lute it well. Then make fire in your furnace to heat your water and let it be no hotter than you may suffer your finger in it. And have at all times warm water to fill your kettle again, when the water by length of time is wasted through the heat of the fire. For if a drop of cold water touches the glass, it will ruin and break asunder. You shall understand that when it drops no more it is clean distilled. Then you must let the glass stand still in it for to cool, for if you draw the glass hot out of it it would break asunder. It is needful for you also to have a round board with a round hole in the middle to lay about the glass to the intent that it may be the longer warm”.
  2. Distillation in the horse belly – the same procedure as in balneo mariae, but in the water “we put horse tordes…because this is a half degre hoter than in balneo mariae, therefore we may distill harder substances in it”.
  3. Distillation in ashes – “We shall put fine sifted ashes in a cappel 7 inches of thickness. Fill the thrice part of a glass with such substance you want and set it in the ashes, than fill the cappelle with ashes until the third part of the glass be covered and the cappelle shall be open?…for if it were of mere copper, through the force and heat of the fire it would melt. After that set the alembick upon the glass and lute it well upon it with lutum sapiencie. Than make a fire under it that it may drop treatably as if you would tell by the clock. And so continue after the same manner for if it fall faster or quicker the fire is too great; therefore stop the wind holes above and beneath than it shal fall the softer and brenne the lesse and so it that smells the less of the fire.
  4. Distillation in sand – similar procedure with 3
  5. Distillation on fire – distilling directly on the fire; appropriate for aqua fortis “and other strong waters”

Distillation of a substance can be obtained via drying of the herbs (this being the main mechanism behind the solar distillation that Brunschwig proposes), filtration (distillation with silt), fermentation, evaporation, etc. To be noted that although Brunschwig’s description of what distillation is depends on his Paracelsian heritage, how distillation can be effected on various substances does not.







Philosophy and scientia (Wissenschaft) in Philipp Melanchthon´s thought

In the latest edition that was dedicated to Philipp Melanchthon´s thought and that emerged as a result of the interdisciplinary workshop held at the Institute for Philosophy at the Free University of Berlin on 28 and 29 October 2010 and published in Berlin and Bretten, 2012, (Der letzte Umbruch), Dr Günther Frank offers a few explanatory remarks concerning the meaning of philosophy in Melanchthon´s sense. He poses the problem of the philosopher which Melanchthon was never regarded as, and brings forth the only scholars that have considered him as such, namely: Wilhelm Dilthey and Hans-Georg Gadamer. In his work of 1892 /1893, Dilthey described Melanchthon as a mediation figure that had carried out the transition between the old “theological-metaphysical System” and the naturalist system of the 17th century.  The debates held by Church historians have been ascribing to Melanchthon influences of the traditions of various schools: he has been regarded as an Aristotelian, Platonist or disciple ofCicero. This line of thought, however operates restrictively and doesn´t manage to cover the whole of his philosophical insight. In the extensive Oeuvre of Melanchthon we can identify three different apprehensions of philosophy.

  1. the Erasmian sense of philosophy, “philosophia Christi” or “philosophia Christiana”

The concept of “philosophia Christi” had been taken by Erasmus from the Church fathers which employed it in a sense that implicated a particular life form, more specifically the life of friars( like in the writings of  Clemens of Alexandria, John Crysostom or Augustin). Erasmus reinterprets the term and bestows on it a new meaning that applies not only to the life of monks, but to all Christians that chose to live according to the teachings of both Church Fathers and the New Testament. This double notion of what a Christian life implies, hardly interested in the speculative perspectives of a theoretical philosophy, is also assumed by Melanchthon-explained in his Declamation to the Paulinian Doctrine. Here, Melanchthon takes the philosophia christi and knits it together with a theology of justification. This declamation is a part of Melanchthon´s early writings in which is influenced by Luther´s critical stance regarding philosophy. His foreword to the 1520 edition of Aristofanes´s Clouds expresses his contempt only for the futility of the speculative philosophy in connection to the political reality. His critical attitude is not, as he will express in a brief letter addressed to the Augustinian Johannes Lang the same year, directed against the philosophers who remain modest and cautions inside of the borders of their own disciplines. As he insists upon in his opening speech of the 1518 school year at Wittenberg- De corrigendis adolescentiae studiis, the liberal arts are not to be given up, but renewed and improved-both Trivium – grammar, dialectics and rhetoric and and Quatrivium: arithmetics, geometry, music, astronomy.

  1. the humanist sense of philosophy

As noted above, Melanchthon aimed at improving and expanding the artes liberales :by introducing history and poetics into the school curricula. He was also bearing in mind the stoic classification of the fields of science: the linguistic, naturalistic and ethical disciplines and named the disciplines of Trivium and Quatrivium as “disciplina humanae” respectively philosophy.

 Günther Frank remarks that there is, strikingly,  no inclusion of moral philosophy in this aim of curricular reform. We can assume that such a conception of Melanchthon´s sense of philosophy-in the strict humanist sense would only narrow down the actual fields of interest which have preoccupied the humanist and foreclose so many philosophical writings that Melanchthon has published: works on Philosophy of law(Cicero), adaptations of Aristotelian psychology(De anima)  that turned out to be extremely important for the history of medicine and for the theory of science (because of the depicted doctrine of the intellect) and of course his contributions to natural philosophy(Initiae Doctrinae Physicae). It becomes obvious that he was not only aiming at reforming the faculty of arts but was also deeply concerned with the higher studies like jurisprudence, medicine and of course, theology. He introduces a philosophical conception of God in theology and philosophical godly proofs. He debates the doctrine of the world´s eternity and the problem of free will. That is how the philosophical stance expands into theological domain.

  1. the universally scientific (universalwissenschaftlich) sense of philosophy

There is a universal, scientific discipline which Philipp Melanchthon has in mind when writing the oration on philosophy in 1536. In a programmatic synopsis of the knowledge which philosophy embraces, the Reformer insists not only on the importance of knowledge of grammar(-a clear hint at the Trivium of the liberal arts) but also the philosophical scientia and so many other arts. He most clearly refers to the important forms of science, as they are described in Aristotle´s Nicomahean Ethics:the theoretic science- obtained through syllogistic demonstration relying on unchanging principles, as well as on things oriented “artes”. Natural philosophy and moral philosophy also belong to the abovementioned encompassing philosophy, like a scientific doctrine of method(dialectics) and the rhetoric. The students who go through such a scientific training, would afterwards obtain a state of mind that would permit them to posses a scientia argumentativa of which Aristotle has explained to be the science of the first, general and unchanging principles. Psychology, philosophy of law and moral philosophy, history, mathematics, astronomy and astrology all are part of this all-encompassing science (ars integra) that is build of this set of sciences. The metaphysics of Aristotle is-of course-not included.

Distillations: what kind of phenomena?

One way to look at the phenomena described by Bacon in the first century of Sylva is through his repeated affirmations that percolation, filtering, distillation etc. are either produced by the same invisible motion or even identical phenomena. What is the source of such affirmations?

A good number of experiments in Century I are taken from Della Porta, Magia naturalis. Does Bacon take over the same classification of phenomena as Della Porta? Or is there a common and accepted meaning of ‘distillation’ containing phenomena as diverse as filtering, separation due to different specific weights, differences of density, condensation, transmutation etc.?


In fact, at the end of the sixteenth century, distillation is a chemical procedure circumscribing a wide range of phenomena. There are a good number of books dealing with this subject, but here is just one example: Conrad Gesner, Thesaurus…de remediis secretis, Zurich, 1555. A best seller: it was translated into English, French, German and Italian and was often republished until 1600. This book is interesting and relevant, I think, because it belongs to one of the most important sixteenth century ‘naturalists’ , and it ‘belongs’ to the tradition of ‘natural history’. Gesner belongs to the tradition of humanist natural history, he is interested in the natural histories (animals, plants, pharmacy and medicine), he is a doctor (in Zurich) a philologist and a collector. He is also opposed to Paracelsianism.

Thesaurus was published in England a couple of times between 1570 and 1600, under different names: The newe jewell of health (translated by George Backer), London, 1676, and The practise of the new and old physicke, London 1599 (the same translation). It is mainly a book on distillation, where by distillation is understood any procedure through which one manages to separate, from a mixed body, thin, aerial or subtle components. It involves heating, vaporization and condensation but the experimental set-up, the apparatus involved or the principles at work can differ widely, according to what the experimenter wants to achieve.

Definitions of distillation

The book begins with a number of definitions of distillation drawn from ancient and modern authors (Langius, Cardano etc.) – the most general involving any separation of elements or particular virtues from a given mixed body. Distillation can be done in various experimental set up (the simplest: bain marie) and it includes filterying drying evaporation etc. Heating is essential, but boiling is not – in fact, Gesner offers a number of slow distillations where the evaporation takes place in the heat of the sun, or by the rays of light augmented through a mirror or a lens.


Theory of matter

Gesner adopts a very curious ‘mixture’ of ‘Atomism’ and Aristotelian matter theory in order to explain the principle of distillation. Here is a significant passage:

No person needeth to doubt, that all Bodies which growe and take increasement in the earth, are compounded of divers, and in a manner, infinitely small parts (which the Greeks properly name Atomes) of the Elements, and that in those rest differing and contrarie vertues: neverthelesse, under one maner of forme of all the Bodies compounded, as the like appeareth, and is confirmed in that roote of Rubarbe, so much regarded and esteemed in all places, which doth both loose the Belie, and bynde the same, yet this delivereth and openeth the obstructions of the Liver (p. 4).

Since in one single plant or substance (having one substantial form) we can find sometimes different (even opposing) qualities and virtues, the question is how can we separate such virtues and incorporate them in medicines or directly in the human organism. Gesner claims that the experimenter should pay attention to two major ‘principles’: the matter subject to distillation, and the apparatus. In this context, he offers a good number of experimental set-ups and apparatuses for various kinds of distillations, from the most simple (‘drawing waters’ of X) to the more complex (involving transmutations, spirits and immateriate virtues).


Classifications and experimental set-ups

Gesner classifies distillations according to the geometry of the experimental set-ups in ascendent and descendent distillations. Also, according to the kind of heat used, distillation can be produced by the heat of the sun (augmented through mirrors and lenses), by the heat of the fire and by the heat emanating from the putrefaction of matter.

The descending distillation can involve a very simple experimental set up, so simple that we can ‘see’ how many of Bacon’s experiments of filtering, percolation etc. can be developed from there. It begins with simply two pots with the mouths joined and buried in the ground (source: Albertus Magnus’ book on distillation). The upper pot is heated and the lower part is the receiver. There is an entire book on the ‘degrees of heate’ needed (moist heat, gentle heat, strong heat etc.). The geometry can also vary. Although the principle is the same, the stillatory can be placed in vessels of different shapes and forms, sometimes even on the top of a tower (p.16).


Common elements

There are three common elements of every distillation: the vessel (a glass bulb with a long neck, or a metallic version of the same), ‘the head’ (see figure) and the receiver. The matter to be distilled is put in the vessel, it gets evaporated and reaches the head, where a process of condensation takes place. The result has to be captured by the receiver.

Although heat is involved in all the distillations described, Gesner also mentions the possibility of distillation to be done ‘by the ice’ (28). What is also interesting is that in the second and third book Gesner is fully aware of the importance of the geometry of the experimental set-ups (for ‘catching’ various volatile components of various substances).

Sylva sylvarum: experiments on transmutation of bodies (24.04.2012)

This meeting followed two important directions: 1) the relation between Bacon’s matter theory and Sylva Sylvarum Century I and 2) the particular discussion of experiments 25 to 30 and the way they connect to the other experiments of Century I. This post deals with the second one.

(25) Experiment solitary touching the making of artificial springs. Before touching the actual experiment, Bacon makes a series of observations about experiments in general that are worth being mentioned. First, we are told that although it may be unexpected, Bacon actually continually rejects experiments. Yet, he tells us that “if an experiment be probable in work and of great use, I receive it, but deliver it as doubtful”: a) How should we understand Bacon’s skeptical attitude towards experiments? b) Does he have a criterion (or criteria) for a trustworthy experiment? Bacon’s constant skeptical attitude towards experiment shows that he does not accept experiments at face value. He seems to believe that some experiments do not provide certain knowledge, and that one has to be constantly aware of the experiment’s limitations, and of its construction, and how this tool should be used for the study of nature. A good demonstration of Bacon’s constant preoccupations with the limits of experiments is the first set of experiments from Sylva, where he criticizes Della Porta’s experiment of filtration of seawater as a bad case of translation (from a natural fact to an artificial fact). Thus, Della Porta’s experiment is taken to be an unreliable experiment whose results are not trustworthy. Consequently, for Bacon, what is important is not whether indeed sand can filter the seawater and make it potable, but the fact that Della Porta’s experiment is not actually telling us anything about that particular phenomenon.

The experiment of an artificial spring goes as follows: On sloping land, a hole is dug, and in the hole a trough of stone is introduced. The hole is covered with brakes and sand. What it is observed, according to Bacon’s source (Bacon did not actually perform the experiment), is that even after the rain stops, a spring of water can be observed at the lower end of the trough. According to Bacon, if this is the case, then this phenomenon can be read as a case of transmutation of air into water because it is as if “the water did multiply itself upon the air, by the help of the coldness and condensation of the earth, and the consort of the first water.”

If this reading is correct, then this experiment should be correlated to experiment 27 which discusses the version and transmutation of air into water. This experiment is interesting in many respects. The experiment cites 4 processes through which air is transmuted to water, or in terms of matter theory, a more pneumatic body (the air) into a more tangible body (the water). Those 4 processes are: condensation (as the example of experiment 25), compression (e.g. distillation vapors, dews), the mingling of moist vapours with air (method suggested for testing via an experiment), and via the porosity of bodies. A few things need to be noted. Bacon grades those 4 processes differently: the first 2 are apparent and sure, the last 2 are considered probable, but not yet manifested. Bacon deals with study cases of these processes later on in Sylva, in an entry entitled Experiments in consort touching the version and transmutation of air into water, where the experiments from 76 to 82 deal precisely with how the ‘version’ is acquired via such processes. The immediate question raised is why Bacon chose to (or did he actually choose to?) separate experiment 27 from experiment 76–82. In fact, experiment 29, entitled Experiment solitary touching the condensing of air in such sort as it may put on weight and yield nourishment, seems to fit well with these experiments. This entry touches on also a process of transition of air, as a pneumatic body (the air) to a denser, tangible body. Bacon’s reasoning is the following: usually for sprouting, seeds/plants are buried in the ground and watered. Yet, some things sprout even if they are only left in the air. Bacon proposes to verify whether those things that sprout in the air increase in weight, thus gain some solid mass. If they don’t increase in weight, then the sprouting is just an inner transformation of the body. If they do increase in weight, then Bacon reasons that the only place where this new mass could come from is the air, which in return would mean that the pneumatic air has transformed into a denser, tangible body. Some things to be noted here: the conclusion Bacon reaches here is dependent on his matter theory. Moreover, we could see the experimental proposal that Bacon makes here as a case of a corroborative evidence for the problem of transforming air into a denser body. A second thing: this experiment could also be used to study the problem of whether air can nourish or not, which is nothing other than a case of translation, one of the methods of experientia literata.

Coming back to experiment 27, we observe that this experiment includes some methodological moves worth mentioning: One of the examples given as a case of transmutation of air into water via condensation is the following: “and the experiment of turning water into ice, by snow, nitre, and salt, would be transferred to the turning of air into water”. Provided the 8 rules of EL, this would be a case of production by extension, since as exp. 82 claims, it “is a greater alteration to turn (artificially) air into water, than water into ice”. The same experimental setup is used to study two different problems: whereas the transformation of water into ice is a case of induration of bodies (a process happening in the same body), the transformation of air into water is a case of transmutation (a case of transition from one species to another).

If a connection seemed apparent between these experiments, we couldn’t trace any ways to connect experiments 26 and 28.

Experiment 26 entitled Experiment solitary touching the venomous quality of man’s flesh. This ‘experiment’ establishes a correlation between cannibalism and its malignant effect for human bodies on the basis of a collection of reported instances of cannibalism. In this example, we could say, in modern terms, that instances are corroborated and that a fact (that syphilis/“the disease of Naples” was originally caused by cannibalism) is considered to be probable precisely because of its status as corroborated evidence. On the other hand, we failed to see how this experiment connects to previous ones or how this experiment could be suggested by any of the others that Bacon has presented so far. Even more, we failed to see what theoretical question underpins it. This also happened with experiment 28, entitled Experiment solitary touching the helps towards the beauty and good features of persons, where Bacon discusses how some of man’s features, while growing, can be moulded by pressure.

Proposals for connecting some experiments:

a. experiments 25, 27, 29, and 76 to 82 appear to study a similar problem—whether a pneumatic body can be transformed into a tangible one

b. experiments 17–23 and experiments 76, 77, 79, and 80 deal with  the problem of how pneumatic matter is “trapped” into bodies, e.g. in infusion, in the pores of bodies . We also alluded to a connection of these experiments with the experiments on percolation (in Sylva’s text, experiments 1 to 8. )

Francis Bacon: Sylva Sylvarum, or a natural history in ten centuries, 1627

The purpose of the seminar this semester is to clarify some of the puzzles and mysteries of Bacon’s most widely read and most puzzling work: the posthumous Sylva  Sylvarum.

Sylva Sylvarum or a natural history in ten centuries was published posthumously (but very soon after Bacon’s death in April 1626) by William Rawley. It was by far  the most widely read of Bacon’s writings, at least in seventeenth century England. It went through 10 editions until 1670 and there were subsequent editions up to the end of the century[1]. There seemed to be 17th editions altogether, plus two Latin editions[2] and a French translation[3]. They not always contain the same texts. The first couple of editions contained unpublished fragments and drafts of Bacon’s natural histories, the subsequent editions contained various other material including, from 1660s on, an abridged English version of Novum Organum. All editions contained New Atlantis. However, in the first editions, this is not explicitly stated on the title page (why?).

As the name indicates, Sylva Sylvarum tended to be seen/read as a collection of materials for building the new science (Bacon is slightly modifying the ancient/Renaissance meaning of Silva, creating a new genre, see De Bruyn, 2001. Traditionally, sylva was used to designate the materials necessary for the construction of a discourse/speech. Bacon is not the first one to move the term in the field of natural history/natural philosophy, however). It contains 1000 “experiments” grouped in 10 groups of 100 (centuries). There are two ‘units’ of SS: solitary experiments and experiments in consort. It is not straightforward what is the meaning of ‘experimetns’ in either of the unit: observation, hearsay, travel reports, questions, suggestions, causal explanations and philosophical questions are mixed both in solitary experiments and in the experiments in consort.

A number of manuscripts relating to Sylva are extant. At least one of them indicates, as Graham Rees has shown (Rees 1981), that the text of Sylva was edited and prepared for publication by Bacon himself. In other words, we don’t have a mere heap of remaining experiments and observations that didn’t find their way into Bacon’s late histories, but a book/project of its own, planned to carry forward the third part of the Instauratio (see also Rawley’s claim). Such an interpretation is substantiated by the historical and contextual paper on the publication of Sylva Sylvarum written recently by Colclough (Colclough 2010).

All this is even more intriguing in view of the fact that Sylva is not only very eclectic but also highly unoriginal (at least “locally”); more than half of the “experiments” are second hand reports following ancient of Renaissance authors, some of them obviously untried by Bacon himself and accepted on dubious testimony.

According to Spedding: “a considerable part of it is copied from the most celebrated book of the kind, Porta’s Natural Magic” (II. 326). However, Spedding himself does not identify all the experiments taken by Bacon from Della Porta. A thorough study of the relation between Sylva Sylvarum and Natural Magic awaits to be written.

Moreover, the experiments Bacon ‘borrows’ from Della Porta, Aristotle, Pliny, Cardano, Sandys, Scaliger etc. are substantially rewritten. They are most of the times more ‘general’ and ‘theoretical’ than the punctual observations and experiments of the sources quoted above. Moreover, Bacon integrate such experiments into a larger scale program: they are the kind of experimental activity that would build up a community of experimental scientists (and in this way, they serve as illustration of the activities of Solomon’s House, see Colclough 2010). They are also a storehouse (or program?) for the future experimental philosophy.

.Questions and puzzles:

1. What is Sylva Sylvarum? (Bacon’s experimental notebook, a treatise of natural history, a plan for another kind of natural history than the Latin natural histories, an illustration of the scientific activities of the Salomon’s House…)

2. What is the relation between the materials assembled in this book and other Baconian writings (esp. natural histories)?

3. Is there a secret order of Sylva? (as Rawley claims in the preface?). Is there any order in Sylva whatsoever and if yes, whose plan/order is it? (Is this volume Rawley’s creation?).


[1] Title pages of the subsequent editions don’t agree on their number or on the content, there are various editions claiming to contain “for the first time” materials published in the previous years etc.

[2] Elzevir 1648, 1661, according to Sarah Hutton, 2001 (to check!)

[3] Pierre Amboise, 1631.