To give an exact and particular Account of the Nature and Manner of acting of Poisons, is no easie Matter; but to Discourse more intelligibly of Them than Authors have hitherto done, not very difficult. One may without much Pains shew their Effects to be owing to something more than the bare Qualities of Heat or Cold; and Discover the Footsteps of Mechanism in those surprizing PhÆnomena which are commonly ascribed to some Occult or Unknown Principle. But to Unravel the Springs of the several Motions upon which such Appearances do depend, and Trace up all the Symptoms to their First Causes, requires some Art as well as Labour; and that both upon the account of the Exquisite Fineness, and marvellous Composition, of the Animal Machine in which they are Transacted, and of the Minuteness of those Bodies which have the force to induce in it such Sudden and Violent Alterations.

I have attempted somewhat this way in the following Essays; in which I do not promise Methodical, and Finish’d Treatises, but only some short Hints of Natural History, and Rude Strokes of Reasoning; which, if put together, and rightly Improved, may perhaps serve to furnish out a more tolerable SPECIMEN of the DOCTRINE of POISONS, than has yet been Published.

The First Draught of this small Piece, I made some Years since, Entertaining my self at Leisure Hours, with Experiments on Vipers, and other Venomous Creatures; Examining now and then the Texture of Arsenic, Mercury Sublimate, and the like Malignant Substances; Turning over what Authors had said on the several Subjects, and making such Remarks as from Time to Time Occurr’d.

There continued Enquiries made up at last, Three or Four short Discourses; which, when I began to Digest into Order, the Increase of Business contracted the Intervals of my spare Time; and the Diversion of such Studies quickly giving way to the Severity of more Necessary Labours, They were quite thrown by, Till Talking not long since with Dr. Areskine, concerning the Viper, I took Occasion to review my scattered Papers, and confirm my Reasonings by New Experiments. He very readily offered Me His Anatomical Observations; These I have put at the End of the First Essay; Which do not promise a Complete Dissection of the Animal, but chiefly shew the Make of those Parts which are concern’d in the Poison.

My Design, in Thinking of These Matters, was, to Try how far I could carry Mechanical Considerations in Accounting for those Surprizing Changes, which Poisons make in an Animal Body; Concluding (as I think, fairly) that if so abstruse PhÆnomena as These did come under the known Laws of Motion, It might very well be taken for granted, that the more obvious Appearances in the same Fabrick are owing to such Causes as are within the Reach of Geometrical Reasoning; And that therefore as the first Step towards the Removal of a Disease is to know Its Origin, so he is likely to be the best Physician, who having the same assistance of Observations and Histories with Others, does best understand the Humane Oeconomy, the Texture of the Parts, Motions of the Fluids, and the Power which other Bodies have to make Alterations in any of These.

Nor indeed ought any One to Doubt of This, who considers that the Animal Compages is not an irregular Mass, and disorderly Jumble of Atoms, but the Contrivance of Infinite Wisdom, and Master-piece of that Creating Power, who has been pleased to do all Things by Establish’d Laws and Rules, and that Harmony and Proportion should be the Beauty of all his Works.

It were therefore heartily to be wish’d, that those Gentlemen who are so much afraid of Introducing Mathematical Studies, that is, Demonstration and Truth, into the Practice of Physick, were so far at least Instructed in the necessary Disciplines, as to be able to pass a true Judgment, what Progress and Advances may be made this way; They would not then perhaps Decry an Attempt of so much Moment to the Wellfare of Mankind, as vain and impossible, because it is difficult, and requires Application and Pains.

It is very evident, that all other Methods of Improving Medicine have been found Ineffectual, by the Stand it has been at these two or three Thousand Years; and that since of late Mathematicians have set Themselves to the Study of it, Men do already begin to Talk so Intelligibly and Comprehensibly, even about abstruse Matters, that it may be hop’d in a short time, if Those who are Design’d for this Profession, are early, while their Minds and Bodies are Patient of Labour and Toil, Initiated in the Knowledge of Numbers and Geometry, that Mathematical Learning will be the Distinguishing Mark of a Physician from a Quack; and that He who wants this necessary Qualification, will be as Ridiculous as one without Greek or Latin.

I have, as to what regards the Animal Oeconomy, Referr’d as much as I could to the Works of Bellini, which have brought great Light into the Dark Regions of Physick, and Taught Us to argue clearly and consistently, instead of Amusing our selves with Unintelligible Words or Precarious Hypotheses. The Dissertations of Dr. Pitcarne, who is the Honour of his Profession in Scotland, are a Convincing Proof of the Advantage of such a Mechanical Way of Reasoning; nor could Malice it self deny This, were not Ignorance in Confederacy with it, which will secure any One from being Benefitted by the most useful Demonstrations.

Notwithstanding This, I have been forced now and then to make Digressions from my Subject, to clear some Doctrines necessary to be known which have not been Explained by others. For indeed the Data from which We argue in these Matters are by many too few. Dr. Cheyne, the Author of the New Theory of Fevers, has enumerated several Particulars in which the Theoretic Part of Medicine still wants Improvement. If these Deficiencies were made good, We might with more Ease Proceed in our Enquiries into Human Nature, and should soon Convince the World, that the most useful of Arts, if duly Cultivated, is more than meer Conjecture, or base Empiricism.

As to the Authors I have made use of, who have Treated of Poisons, I have Quoted only those who Furnished me with Matter of Fact; For there are but few Originals; and very large Volumes on this Subject do many times contain little more than a Collection of Vulgar Errors.

I had once Thought to have carried these Searches farther; in Particular, besides what is occasionally mention’d in the last Essay concerning Infection in acute Diseases, to have enquired into the Nature of Contagious and Hereditary Distempers. But the Humour of Scribling would not hold out; And some perhaps will say, ’Tis well enough it didn’t; For I am not Ignorant how Few I am like to Please; If it be hard to Think and Write Justly, ’tis harder yet to Bring Others to one’s own Taste; Nor shall I be at all Angry, if to Many I have afforded Matter of Satyr and Invective; Less Wit suffices for These than for the Discovery of Useful Truths. They who have no Smattering of Mathematical Knowledge, are incompetent Judges of what Service I have done towards the Improvement of the Theory, or Practice of Medicine, and Those who are acquainted with these Matters, will, it may be, think it something to Talk Intelligibly on such difficult and abstruse Points. I neither want Applause, nor fear Censure; and therefore be the Fate of These Papers what it will, as they were first Penn’d for my own Satisfaction, and Innocent Entertainment; so I am resolved They shall never Ingage me in the Trouble of Quarrels or Disputes.