medicines he introduced into the practise many remedies not authorized nor sanctioned by the medical schools. Preparations of antimony, iron, mercury and opium were prominent among these, and apparently were employed with success in his own practise. To the chemists he especially appealed to abandon the vain search for the making of gold and silver—"the threshing of empty straw"—and to devote their energy and skill to the preparation of new remedies, and to their application to medicine.
But few of the works of Paracelsus were printed during his lifetime. In several cases the reason for this can be directly traced to the opposition of the medical faculties and their influence upon the public censors or publishers. But he did not cease writing on that account, and some twenty years after his death there began the active publication of his manuscripts. Some of these were autograph manuscripts—others more or less complete copies, or lecture notes edited or expanded by former pupils—some of doubtful authenticity, and others known to be fabrications published by anonymous writers. It is still difficult in many cases to be certain as to the authenticity of some of the many treatises attributed to him. Their popularity and influence during the succeeding century was very great, as is evidenced by the fact that the Paracelsus bibliography by Sudhoff enumerates no less than 390 titles of printed publications up to 1658, when the last and best known Latin edition of his collected works made its appearance. Among these were four editions of his collected works in German and two in Latin.
Through the mass of writings of Paracelsus are scattered, rather than systematically gathered, the chemical facts and theories which comprise his contribution to chemical literature. Together they form a considerable body of chemical knowledge, descriptions of chemical processes and substances known in his time with much of speculative theory. There is no evidence that he added in any important way to the chemical knowledge of his time. Though the first announcement of some chemical facts appear in his writings, he makes no assumption of originality in their announcement, any more than do Agricola and Biringuccio in their works. It was rather by his evident familiarity with the chemistry of his time, and the novel and radical application of chemical preparations in the practise of medicine, that he challenged the attention of the chemists of his time. Here his influence was epoch-making. In the field of chemical theory he shows greater originality, and while much of his speculations are fantastic in the fashion of the philosophy of the time, yet in other directions he exerted important influence.
One very influential contribution to chemical theory, however, is to be attributed to Paracelsus. This was the theory of the three principles—the "tria prima." It will be remembered that the early alchemists had recognized the peculiar relation of sulphur to the occur-
