The term “iatro-chemistry” denotes a particular phase in the history of medicine and of chemistry. The iatro-chemists were a school of physicians who sought to apply chemical principles to the elucidation of vital phenomena. According to them, human illnesses result from abnormal chemical processes within the body, and these could only be counteracted by appropriate chemical remedies. Although this idea did not originate with him, the chief exponent of this school is commonly said to be Paracelsus.

A man of violent passions, coarse, drunken, arrogant, and unscrupulous, Philippus Aureolus Theophrastus Paracelsus Bombastus von Hohenheim—to give him his full name—would seem to have possessed none of the attributes needed by the successful leader of an intellectual revolution.

Born at Etzel in Switzerland in 1493, son of a physician, William Bombast von Hohenheim, who combined the practice of astrology with that of alchemy, Paracelsus, even as a youth, became a wanderer, passing from province to province and cloister to cloister, living by telling fortunes and practising sometimes as a quack and at other times as an army surgeon, and gaining, as he tells us, much curious information from old women, gipsies, conjurers, and chemists. If we may trust his own account of himself, he had, before he was thirty-three, wandered over the whole of Europe, and even into Africa and Asia, everywhere performing miraculous cures and constantly getting into trouble. In 1526 he secured the appointment of Professor of Physic in the University of Basle, and signalised his occupancy of the chair by a course of lectures—a farrago of confused German and barbarous Latin—in which he assailed with extraordinary vigour and unexampled coarseness the medical system of the school of Galen. Scandalised as his professional brethren might be, Paracelsus expressed, intentionally or unintentionally, the feeling of impatience with which the laity viewed a system of therapeutics based only on tradition. In this revolt against authority he initiated a movement which, whatever might have been its influence on medicine, served eventually, under the guidance of worthier men, to emancipate chemistry from the thraldom of alchemy.

Paracelsus did little more than initiate. Although his many tracts show that he was familiar with nearly every chemical preparation of his time, many of which he used in his practice, he added no new substance to science. A man of great ability and extraordinary talent, he squandered his powers in dissipation. His intemperate conduct soon lost him his chair at Basle; and, after an ignoble quarrel with the magistracy, he fled the town, and, resuming his wandering life, died, under wretched circumstances, at Salzburg, in his forty-eighth year.

Space will not permit of any account of the philosophical opinions of Paracelsus—of his mysticism, his theosophy, his pantheism, his extraordinary doctrine of the ArchÆus and Tartarus, his association of astrology with medicine. His chief merit lies in his insistence that the true function of chemistry was not to make gold artificially, but to prepare medicines and substances useful to the arts. He thereby made chemistry indispensable to medicine, and thenceforward chemistry began to be taught in the universities and in the schools as an essential part of a medical education.

Paracelsus is usually regarded as a typical alchemist—the kind of man made familiar to us by the paintings of Teniers, Van Ostade, and Stein—a boorish, maudlin knave, who divided his time between the pothouse and the kitchen in which he prepared his extracts, simples, tinctures, and the other nostrums which he palmed off upon a credulous world, as ignorant and superstitious as himself. There is much in the personal history of Paracelsus that serves to justify such a view of him. That he was in the main an impudent charlatan, ignorant, vain, and pretentious, there can be little doubt. He had an astonishing audacity and a boundless effrontery; and it was largely by the exercise of these qualities that he secured such professional success as he enjoyed.

To judge from the number of the published works associated with his name, he was an active and industrious writer. Considering that during the greater part of his waking time he was more or less intoxicated, it is difficult to conceive what opportunity he had for composing them. Only one or two are known to be genuine. These, according to Operinus, his publisher, he dictated; and from their incoherence and obscurity, their mystical jargon, and misuse of terms, they read like the ravings of one whom drunkenness had deprived of reason. Many of the tracts and larger works appeared after his death—some of them years after; and there is no certain proof that he was the actual author. Even if we regard them as suppositious, the fact that they should be published under his name is significant of the influence and notoriety which this extraordinary man succeeded in achieving during his short and chequered career.

The immediate followers of Paracelsus—among whom may be named Thurneysser, Dorn, Severinus, Duchesne—distinguished themselves only by the boldness with which they promulgated his doctrines, and the unscrupulous use which they made of his methods. They were all zealous anti-Galenists, who professed to believe that the sum and perfection of human knowledge was to be found in the Cabala, and that the secrets of magical medicine were contained in the Apocalypse. They adopted pantheism in all its grossness: everything that exists eats, drinks, and voids excrement; even minerals and liquids assimilate food, and eliminate what they do not incorporate. Sylphs inhabit the air, nymphs the water, pigmies the earth, and salamanders the fire. Thus even the Aristotelian elements were animated. Mercury, sulphur, and salt were, according to Paracelsus, the primal principles which entered into the composition of all things, material and immaterial, visible and invisible. The following so-called “harmonies” were essential articles of faith with a Paracelsian:—

The laws of the Cabala were held to explain the functions of the body. The sun rules the heart, the moon the brain, Jupiter the liver, Saturn the spleen, Mercury the lungs, Mars the bile, Venus the kidneys. Gold was a specific against diseases of the heart; the liquor of Luna (solution of silver) cures diseases of the brain. “The remedies,” said Paracelsus, “are subjected to the will of the stars, and directed by them. You ought, therefore, to wait until heaven is favourable before ordering a medicine.”

The Paracelsian physicians, for the most part, were a set of dangerous fanatics, who, in their contempt for the principles of Hippocrates, Galen, and Avicenna, and in their reckless use of powerful remedies, many of them metallic poisons, wrought untold misery and mischief. The inevitable reaction set in, and certain of the faculties, particularly that of Paris, prohibited their licentiates, under severe penalties, from using chemical remedies. It is not to be supposed, however, that all iatro-chemists were unscrupulous charlatans. Some of them clearly perceived the significance and true value of the movement which Paracelsus may be credited with having originated.

Andreas Libavius, or Libau, originally a physician, born in Halle, is best known by his Alchymia, published in 1595, which contains an account of the main chemical facts known in his time, and is written in clear and intelligible language, in strong contrast to the mystery and obscurity of his predecessors. He was the discoverer of stannic chloride, still known as the fuming liquor of Libavius, and described a method of preparing oil of vitriol in principle identical with that now made use of on a manufacturing scale. He died in 1616.

John Baptist van Helmont, a scion of a noble Brabant family, was born in Brussels in 1577. After studying philosophy and theology at the University of Louvain, he directed his attention to medicine, and made himself familiar, in turn, with every system from Hippocrates to Paracelsus. Having spent some time in travel, he settled on his estate at Vilvorde, and occupied himself with laboratory pursuits until his death in 1644.

Van Helmont was a scholarly, studious man, and a philosopher. A theosophist and prone to mysticism, he had many of the mental characteristics of Paracelsus, without his fanaticism and overweening egotism. He narrowed the number of Aristotle’s elements down to one, and, like Thales, considered water to be the true principle of all things, supporting his theory by ingenious observations on the growth of plants (see p.20). He first employed the term gas, and was aware of the existence of various Æriform substances, anticipating Hales, who has been styled the father of pneumatic chemistry, in the discovery of many gaseous phenomena. He gave an accurate description of carbonic acid gas, which he termed gas sylvestre, and showed that it is produced from limestone and potashes in the fermentation of wine and beer, and that it is formed in the body and in the earth. The doctrines of the iatro-chemists were further spread by Sylvius in Holland, and by Willis in England.

Francis de le BoË Sylvius, born at Hanau in 1614, became Professor of Medicine in the University of Leyden, where he exercised great influence as a teacher until his death in 1672. Medicine he treated simply as a branch of applied chemistry, and the vital processes of the animal body as purely chemical. He freed the theory of physic from much of the mystical absurdity introduced into it by Paracelsus and van Helmont, and by his practice brought chemical remedies once more into vogue. He was aware of the distinction between venous and arterial blood, and that the red colour of the latter was due to the influence of air. Combustion and respiration he regarded as analogous phenomena.

Thomas Willis was born in Wiltshire in 1621, and while a student at Christchurch bore arms in the Royalist army when Oxford was garrisoned for Charles I. In 1660 he became Sedleian Professor of Natural Philosophy, and ultimately settled in London as a physician. He died in 1675, and was buried in Westminster Abbey.

Willis imagined that all vital actions were due to different kinds of fermentation, and that diseases were caused by abnormalities in the fermentative process. Although a Paracelsian as regards his theory of the constitution of matter, he followed Sylvius and his pupil Tachenius in banishing mysticism from medicine. He was a skilful anatomist, and gave the first accurate description of the brain and nerves.

Other notable iatro-chemists were Angelus Sala, Daniel Sennert, Turquet de Mayerne (who became body physician to James I.), Oswald Croll, Adrian van Mynsicht, and Thomas Lieber. Croll introduced the use of potassium sulphate and succinic acid into medicine, and Van Mynsicht that of tartar emetic. Various antimonial preparations had previously been employed by chemical physicians since the time of Basil Valentine, despite the ban of the Parliament of Paris on their use.

The chief service of iatro-chemistry to science consisted in its influence in bringing chemistry within the range of professional study, whereby a great extension in its pursuit was effected, with the result that a largely increased number of substances was discovered. Moreover, this wider experience of chemical processes familiarised workers with chemical phenomena in general, and thereby contributed to lay the foundations of a general theory of chemical action, which a succeeding age strove to complete.

During the period of iatro-chemistry, which may be said to have extended from the first quarter of the sixteenth century to the latter half of the seventeenth, chemistry was advanced along practical lines by the labours of many men, chief of whom were Agricola the metallurgist, Palissy the potter, and Glauber the technologist. These men were primarily experimental chemists, who took little or no part in the fruitless polemics of the period, but followed their avocation in the true spirit of investigators, and thereby enriched science with many new and well-ascertained facts.

George Agricola, born at Glauchau in Saxony in 1494, was a contemporary of Paracelsus. After studying medicine at Leipzig, he devoted himself to metallurgy and mineralogy, first at Joachimsthal, and published a number of works which were long deservedly regarded as the leading treatises on these subjects.

In his Libri XII. de re Metallica he gives an account of what was known in his time respecting the extraction, preparation, and testing of ores. He describes the smelting of copper and the recovery of the silver which might be associated with it. He also describes methods of obtaining quicksilver, and of purifying it by treatment with salt and vinegar. He gives a full description of the method of obtaining gold by amalgamation, and of recovering the mercury by distillation. He gives accounts of the smelting of lead, tin, iron, bismuth, and antimony, and describes the manufacture of salt, nitre, alum, and green vitriol.

The whole work, which is of folio size, is illustrated by wood-cuts, which give a faithful idea of the nature of the several operations, and of the character of furnaces, trompes, bellows, and tools employed in them. It is by far the most important technical work of the sixteenth century, and it exercised great influence on the art of metallurgy. The descriptions—at least as regards European processes—are evidently the result of personal observation. Agricola visited the mines, and faithfully noted the different methods of sorting and washing the ores, the characters of which he accurately describes. His accounts of the various smelting operations are so detailed that it is obvious they must have been put together after personal inquiry. The study of metallurgy, indeed, was the main object of his life; and he devoted to its pursuit even the pension which had been settled on him by Maurice, Elector of Saxony. He became Mayor of Chemnitz, died there in 1555, and was buried at Zeitz.

Bernard Palissy lived throughout the greater portion of the sixteenth century. Although not a professed chemist, nor a follower of any particular school, he was an ardent self-taught experimentalist and a keen and accurate observer, who greatly enriched ceramic art by his discoveries.

Johann Rudolf Glauber was born at Karlstadt, in Bavaria, in 1604, and after a restless life died in Amsterdam in his sixty-fourth year. He published an encyclopÆdia of chemical processes, in which he describes the preparation of a great variety of substances of technical importance. The greater number of the pharmacopoeias of the seventeenth century are indebted to him for their descriptions of the mode of manufacture of their official preparations. He discovered sodium sulphate—his sal mirabile, still frequently named after him—and introduced it into medicine.

During this period the common mineral acids—sulphuric, hydrochloric, and nitric—became ordinary articles of commerce, and were used in the manufacture of a number of useful products, chiefly inorganic salts. A considerable number of metallic oxides were also in common use, and were applied to a variety of purposes in the arts. The knowledge of definite organic substances was much more limited. Acetic acid had long been known, but was first obtained in a concentrated form during this period by the distillation of verdigris. A number of other acetates were also known, as well as certain tartrates—as, for example, salt of sorrel, Rochelle or seignette salt, and tartar emetic. Succinic and benzoic acid were introduced into medicine, and Tachenius discovered one of the characteristic acids of fat and oil (stearic acid). Spirit of wine was, of course, largely made and used in the preparation of tinctures and essences. Ether, originally known as oleum vitrioli dulce verum, was first discovered by Valerius Cordus; and a mixture of it with alcohol, long known as Hoffmann’s drops, appears to have been employed as a medicine by Paracelsus.