It may be proper, perhaps, to state here, in a very few words, the objects which the author had in view in drawing up the following History of Chemistry. Alchymy, or the art of making gold, with which the science originated, furnishes too curious a portion of the aberrations of the human intellect to be passed over in silence. The writings of the alchymists are so voluminous and so mystical, that it would have afforded materials for a very long work. But I was prevented from extending this part of the subject to any greater length than I have done, by considering the small quantity of information which could have been gleaned from the reveries of these fanatics or impostors; I thought it sufficient to give a general view of the nature of their pursuits: but in order to put it in the power of those who feel inclined to prosecute such investigations, I have given a catalogue of the most eminent of the alchymists and a list of their works, so far as I am acquainted with them. This catalogue might have been greatly extended. Indeed it would have been possible to have added several hundred names. But I think the works which I have quoted are more than almost any reasonable man would think it worth his while to peruse; and I can state, from experience, that the information gained by such a perusal will very seldom repay the trouble.

The account of the chemical arts, with which the ancients were acquainted, is necessarily imperfect; because all arts and trades were held in so much contempt by them that they did not think it worth their while to make themselves acquainted with the processes. My chief guide has been Pliny, but many of his descriptions are unintelligible, obviously from his ignorance of the arts which he attempts to describe. Thus circumstanced, I thought it better to be short than to waste a great deal of paper, as some have done, on hypothesis and conjecture.

The account of the Chemistry of the Arabians is almost entirely limited to the works of Geber, which I consider to be the first book on Chemistry that ever was published, and to constitute, in every point of view, an exceedingly curious performance. I was much struck with the vast number of facts with which he was acquainted, and which have generally been supposed to have been discovered long after his time. I have, therefore, been at some pains in endeavouring to convey a notion of Geber’s opinions to the readers of this history; but am not sure that I have succeeded. I have generally given his own words, as literally as possible, and, wherever it would answer the purpose, have employed the English translation of 1678.

Paracelsus gave origin to so great a revolution in medicine and the sciences connected with it, that it would have been unpardonable not to have attempted to lay his opinions and views before the reader; but, after perusing several of his most important treatises, I found it almost impossible to form accurate notions on the subject. I have, therefore, endeavoured to make use of his own words as much as possible, that the want of consistency and the mysticism of his opinions may fall upon his own head. Should the reader find any difficulty in understanding the philosophy of Paracelsus, he will be in no worse a situation than every one has been who has attempted to delineate the principles of this prince of quacks and impostors. Van Helmont’s merits were of a much higher kind, and I have endeavoured to do him justice; though his weaknesses are so visible that it requires much candour and patience to discriminate accurately between his excellencies and his foibles.

The history of Iatro-chemistry forms a branch of our subject scarcely less extraordinary than Alchymy itself. It might have been extended to a much greater length than I have done. The reason why I did not enter into longer details was, that I thought the subject more intimately connected with the history of medicine than of chemistry: it undoubtedly contributed to the improvement of chemistry; not, however, by the opinions or the physiology of the iatro-chemists, but by inducing their contemporaries and successors to apply themselves to the discovery of chemical medicines.

The History of Chemistry, after a theory of combustion had been introduced by Beccher and Stahl, becomes much more important. It now shook off the trammels of alchymy, and ventured to claim its station among the physical sciences. I have found it necessary to treat of its progress during the eighteenth century rather succinctly, but I hope so as to be easily intelligible. This made it necessary to omit the names of many meritorious individuals, who supplied a share of the contributions which the science was continually receiving from all quarters. I have confined myself to those who made the most prominent figure as chemical discoverers. I had no other choice but to follow this plan, unless I had doubled the size of this little work, which would have rendered it less agreeable and less valuable to the general reader.

With respect to the History of Chemistry during that portion of the nineteenth century which is already past, it was beset with several difficulties. Many of the individuals, of whose labours I had occasion to speak, are still actively engaged in the prosecution of their useful works. Others have but just left the arena, and their friends and relations still remain to appreciate their merits. In treating of this branch of the science (by far the most important of all) I have followed the same plan as in the history of the preceding century. I have found it necessary to omit many names that would undoubtedly have found a place in a larger work, but which the limited extent to which I was obliged to confine myself, necessarily compelled me to pass over. I have been anxious not to injure the character of any one, while I have rigidly adhered to truth, so far as I was acquainted with it. Should I have been so unfortunate as to hurt the feelings of any individual by any remarks of mine in the following pages, it will give me great pain; and the only alleviation will be the consciousness of the total absence on my part of any malignant intention. To gratify the wishes of every individual may, perhaps, be impossible; but I can say, with truth, that my uniform object has been to do justice to the merits of all, so far as my own limited knowledge put it in my power to do.