that all objects in the world were composed of air, earth, water, and fire, in which, after all, they were right enough. It has been supposed, too, that among the Egyptians at least, speculations were entertained to the effect that metals were compound in their nature, and some alchymists of a later date claimed the so-named Trismogistus as the founder of their art. But this is not supported by evidence, and quite contrary to all that history teaches us, of the progress of science. At first of all, (and indeed this holds good in almost everything connected with the mind of man,) isolated facts are diligently and laboriously stored; next in the healthy tone of early society, these, or some of these, are referred to principles, and these principles are more or less dogmatically taught. Rational dogmatism is created and transmitted to after generations, and always remains, however much it may suffer from passing clouds, the orthodox party. It is it that philosophically corrects previously established principles, that improves previous principles, or that adds new ones, always operating by the induction from observation of new facts, as connected with previous induction from previously observed facts. After a time two other plans of considering science invariably spring up. The one is that of Methodism, which, disdaining the cautious progress of rational dogmatism, striking out some new plan of her own, not from observation of facts, and consequent deduction, but from a fanciful hypothesis, or method, (whence the early name of this group of philosophical sectaries,) which is assumed as a law. The other is that of Scepticism or Empiricism, which denies the power of the human mind to generalize, and affirms that nothing is possible save for each individual to watch isolated facts. At any rate we shall see that this law holds true with regard to chemistry.

Some portion of the chemistry of the Egyptians, the Greeks, and the Romans, had doubtless from time to time spread to Persia, to India, and to Arabia, but after the fall of the Roman empire chemical science was in abeyance, until the brilliant outbreak of the Mahommedan Arabs. From the founding of Bagdad, in the eighth century, to the decadence of the Arabians in the twelfth, they not only incessantly cultivated chemistry, and added very materially to its stores, but they created the school that existed among the western Christians from the twelfth to the sixteenth century. Indeed, they did more, for it was

amongst them that the first great methodical sect, that of the alchymists, arose.

In considering the history of the Arabian school, of which Geber and Avicenna may be named as the most illustrious members, it is necessary to remember that our knowledge regarding it is very imperfect. The Arabian chemists certainly very much affected the progress of chemistry, and in consequence of so doing became acquainted with many chemical compounds that were unknown to their predecessors. It is now, however, quite impossible to define the chemical theories of the purely Arabian school, and any consideration of them may be here omitted. It is, indeed, of more importance to notice the fact, that among the Arabians the study of chemistry was combined with the practice of medicine, and that mineral acids, alkalies, and metallic salts, were not only known, but therapeutically used. This was not the case among previous medical men, and the innovation (certainly an improvement) ultimately lead to important results.

Of all the events, however, that characterized the Arabian chemists, the most interesting was the rise and progress (at least on a large scale) of alchemy. The general idea of this was, that the metals were all compound substances, that the baser metals, as they called them, differed from gold merely in containing various contaminations, and that if these contaminations could be got rid of, pure gold would be the result. Considered in the abstract, alchemy is not unphilosophical. When we say now-a-days that the metals are elementary bodies, all that we mean is, that we cannot resolve any metal into two elements, although it is quite possible that this may be done. The absurdity of alchemy was this, that its votaries did not from facts deduce the compound nature of metals, and then try to separate the pure part from the impure, according to the proceedings of the rational dogmatists, but they took the theory first and hoped the facts would follow. Alchemy was the first great outburst of methodism as applied to chemistry. The principle of alchemy may become the established principle of our day, but if so it will be, at least it is to be hoped it will be, honestly and scientifically come by. But it was not so with the alchemists.

The notion that we have of the so-called philosophical stone that was to effect the purification of the metals, is

probably very different from that of the Arabian methodics. Much as we are entitled to blame the false methodic system of the alchemists, this powder of projection was probably a methodical preparation, and not, as modern writers assert, a mere empirical substance. Methodism is indeed an aberration from right thinking, a sort of delirium as it were, but not a total deprivation of it, as empiricism is. This philosopher's stone subsequently, and perhaps long subsequently, came to be also regarded as the powder of life, or panacea for all diseases, and preventer of the debility of old age.

The chemical school that arose in the twelfth and three succeeding centuries among the Christians of the west, was derived from the Arabs, and was certainly strongly tinged with alchemy. Alchemy, with its powders of projection, would have lost its patent character of methodism, so totally opposed in its spirit to mediæval, or at least to mediæval Christian, orthodoxy. But we have probably jumped far too rapidly to the conclusion, that alchemy was all, or, indeed, anything but a very subsidiary part of the medieval chemistry. On the contrary, it was probably more of a speculation than anything else, and not an article of scientific faith so much as a source of investigation as a relaxation.

Almost every one of these early Christian alchymists were members of monastic institutions. The earliest of these who attained a reputation was Albertus Magnus, who died at an extreme old age, towards the close of the thirteenth century. He was a Dominican, and at one time bishop of Ratisbon, but being released from his episcopal charge, he retired to his monastery at Cologne, where his time was mainly occupied by scientific pursuits. He was not only acquainted with many chemical processes and products not known to the Arabs, but many of his opinions have become accepted doctrines of chemistry. He considered the metals to be compounds of mercury, sulphur, and water, and believed in the possibility of separating the gold that he thought to be contained in the inferior metals. St. Thomas Aquinas was a pupil of his, and his chemical writings are remarkable as containing some now-familiar chemical expressions. But we may perhaps take as the type of this school, Roger Bacon. Amongst the various branches of learning that this great man investigated, chemistry was one, and it is plain from

his writings, that although he held the view of the compound nature of metals, his attempts at extracting gold were based upon principles quite compatible with science and philosophy, and his only statements about the reality of the philosopher's stone are, that others affirmed that they possessed it. In this respect his memory has been very unjustly calumniated by Voltaire. Bacon is surely no more to be blamed for speaking of others affirming that they could manufacture gold, or construct the powder of life, than any one now-a-days would be for speaking of mesmeric trances, or the affirmed results of homoeopathy, although he knew the absurdity and falsehood of both.

These early religious chemists were probably also medical practitioners. Galen, however, was still a standing authority, and few remedies save Galenical ones, i.e., those derived from the vegetable world, were employed. Some chemical drugs were, however, doubtless beginning to be used, and Basil Valentine, a Saxon monk, paved the way, in the fourteenth century, for an innovation in this respect, that had much influence upon chemistry. He introduced antimonials into practice, and is said to have experimented upon his brother monks with them with such bad results, that the metal has been called antimony, Οι αντι μόνος ever since.

But a strange innovation was at hand, and for the first time Pyrrhonism dawned upon the science. The empiric Paracelsus-the Luther of chemistry-appeared. Like Luther, Paracelsus had the desire to attack what was believed, to throw his whole soul and energy into the contest, and after all to merely destroy, and to build up nothing in the place of that which was gone. Paracelsus introduced into chemistry the spirit of scepticism. His first public professional act was to burn publicly the writings of Galen and Avicenna, and, curiously enough, he first commenced the discontinuance of the use of the learned languages in teaching, and substituted the vernacular. His own beard, he said, contained more knowledge than all the universities, and the hairs of his head more than that of all previous physicians. As if to keep up the parallel with Luther, Paracelsus was, although like Luther essentially a Pyrrhonist, excessively superstitious upon many points, and believed, or affected to believe, in the doctrine of signatures, and other fancies as absurd. Paracelsus closed his troubled and vagabond life in 1541.

In one sense Paracelsus inflicted a severe blow upon the science of chemistry, but indirectly, and ultimately, he certainly promoted its progress. To attack what is believed, possibly believed with affection, simply because it is established belief, and the preaching up of empiricism are always dangerous enough, but in this, as in other analogous cases, out of danger comes safety. The superstitious and otherwise absurd doctrines of Paracelsus and his (happily, few) followers, were soon neglected and forgotten, but the faith in the efficacy of mineral or chemical remedies, as they came to be called, in opposition to the Galenical ones, remained, and what was of more impor tance still, (for a great many mineral drugs might, after all, safely be dispensed with,) chemistry became to be recognized as an essential branch of medical education, and from this time every physician was more or less of a chemist, a procedure that has subsequently brought about very beneficial results.

The purely empirical school of Paracelsus speedily and naturally died. We say naturally, for empiricism being the product of an individual, dies with the individual. But chemistry had received such a shock from her encounter with these practical innovations, that the dogmatic school did not at once assume its sway, but methodism again obtained the supremacy. Van Helmont was the founder of this new methodic sect. Born in the last quarter of the sixteenth century, he studied philosophy at Louvain, and there attended the prelections of the Jesuits of that city, but he took no degree. He became next a diligent student of the writings of Thomas à Kempis and of Taulerus, and he endeavoured to draw an analogy between physical science and the operations of divine grace. From a spirit of mortification he surrendered his property to his sister, studied medicine in order that he might be of use to the poor, and endeavoured to build up a system of general material philosophy, including, of course, chemistry.

This system was not that of a rational dogmatist, but essentially methodic, and therefore its details need not detain us long. He assumed the existence of an imaginary principle, which he named the archæus, and which he maintained had some mysterious power of drawing the particles of matter together by means of the process of fermentation. Only two causes of matter, he said, existed,