A Mechanical Account of Poisons in Several Essays

by Richard Mead

To understand aright how all this is done, it is necessary to hint somewhat concerning the Nature of Fluids in General, and those Alterations in them which we call Fermentations; for I shall retain this known Word, tho’ in the proper Sense in which ’tis commonly used, there can be no Fermenting of the Liquors in the Animal Body.

And here I must refer to the Treatise of Bellini de Fermentis, who has with great Clearness shewn, that there is in all Fluids not only a simple Contact of their Parts, but also a nisus in Contactum, or Cohæsion, and this of a certain Degree or Force, and besides, of a particular Direction; which is indeed, tho’ express’d in other words, the very same thing with the Attraction of the Particles one to another; This Mr. Newton has demonstrated to be the great Principle of Action in the Universe, has taught us the Laws of it in the greater Quantities and Collections of Matter; and he who rightly Studies his Philosophy will understand that the same obtains in the most Minute and Finest Corpuscles, which do unite into Bodies of different Solidity and Make, according to the Degree with which they do mutually attract each other, and to the Superficies, by which, when drawn, they do touch and adhere. To this if we add a Pression of the several Parts of the Fluid every way, and consider withal, that this Uniform Attraction of the Parts to one another must be variously changed by the different Attraction of Heterogeneous Bodies mixt with them, we have the great Principles of all Fluids, upon which their several Phænomena do depend.

And hence it follows, that whatsoever Power is sufficient to make a Change in this Attraction, or Cohæsion of the Parts, makes an Alteration of the Nature of the Fluid; that is, as the Chymists express it, puts it into a Fermentation. And if any one shall think it necessary to enquire into the particular Manner of producing such an Effect, we may perhaps in so abstruse a Matter not improbably Conjecture thus, That our Blood consisting chiefly of Two Parts, a simple Lymph, and an infinite Number of small Globules, containing a very subtle and elastic Fluid, these acute Salts, when mingled with it, do prick those Globules, or Vesiculæ, and so let out their imprisoned active Substance, which expanding it self every way, must necessarily be the Instrument of this speedy Alteration and Change [(15)]. From such an Hypothesis as this (and, it may be, not very easily from any other) we may account for many of the surprizing Phænomena in the Fermentations of Liquors; and as precarious as it seems, its Simplicity, and Plainness, and Agreement with the forementioned Doctrine, will, I believe, recommend it before any other to those who are not unacquainted with Geometrical Reasonings. But I wave these Considerations at present, and shall only add One Remark or Two with Relation to the purpose in Hand, and so proceed.

In the first place then, we may from this Theory, learn, how it comes to pass that so small a Portion of Juice should infect so great a quantity of Liquor; for in order to do this, it is not necessary that the Venom should be at the very first mixt with all its Parts; but it is sufficient that it prick some of the Bladders, and the elastic Matter of these being let out, will be a nimble Vehicle to the acute Salts, and not only by its activity disperse them thro’ the Fluid, but restore to them their decreasing Force, and thus continue their Effects, till a great part of the Liquor undergoes at least, in some Degree, the like Alteration.

And this will the more easily happen in the present Case, because the Force with which this Poison is thrown into the Blood, as appears from the Mechanism of the discharging Organs, is very great, and consequently its Effects will be proportionably violent, or the Mischief more large and diffused.

The want of this may be one Reason why the Experiment of first making a Wound in the Flesh with any sharp Instrument, and then dropping in the Sanies, may not always succeed so well in killing Animals, as one would from the preceeding Doctrine be ready to expect. Tho’ if some amends be made for this Defect, by taking a greater quantity of the Juice, and carefully instilling it, It proves equally Fatal this way, as when immediately discharg’d from the Viper it self. Thus it might happen that those Trials of this kind, which were happily made by S^r Redi, might not however convince M^r Charas, in as much as there is oftentimes a great deal of difference in the Event of Experiments, when made with Purpose, and a Design that they should succeed, and when Timorously and Cautiously managed, lest they should unluckily overthrow a darling Hypothesis.

The other Observation I shall draw from the foregoing Theory, is this, That it appears from hence what a vast variety there may be in the Fermentations even of one and the same Fluid; for these being no other than Changes made in the Cohæsion of the compounding Particles, are capable of as many Alterations as Motion in its Degrees and Directions can admit of, which are really Infinite.

This I mention with regard to some of the following Essays, in which, if we ascribe many Symptoms seemingly very different, to a Ferment rais’d in the Blood, it may be consider’d, that the Nature of this Cause is such, as according to the several Properties of the Primum Agens, or Fermenting Power, to bear by far more Varieties than any one can be aware of.

To return to the Viper; the Effects of such an Agitation of the Blood, as we have been describing, must not only be whatever are the Consequences of a disturbed Circulation, and irregular and interrupted Secretion of the Spirits, as low Pulse, Faintings, Sickness, Palpitation of the Heart, Convulsive Vomitings, Tremblings of the Body, &c. but also the Texture of this Fluid being thus broken, those Parts of it which are of the slowest Motion, and greatest Viscidity, will be easily separated from the others; such they are, which when united together do compound the Bile, and therefore these will tinge the Capillary Vessels, and fine Ducts in the Skin, with a Yellowish Colour; that is, will induce an Icterus, or Jaundice.

For it is not only (if at all Primarily) from an Obstruction of the Biliary Canals that this Symptom does proceed, but also from any Cause whatsoever, which either destroys the Saline Part of the Bile, by the means of which its Oil is kept mixt with the Water of the Blood, or else increases the Oily and Sulphureous Part to that Degree, that tho’ it be duly impregnated with Salt, yet the Watery Part of the Blood, which can only take up a certain Proportion of it, being already Saturated, can receive no more; or lastly, does, by disuniting the compounding Particles of the Blood, alter that Intestine Motion and Agitation which is necessary to carry along thro’ the Vessels, together with the more volatile Parts, those which are more Clammy and Glutinous. For in all these Cases ’tis plain that the Bilious Corpuscles must be præcipitated upon those Parts of the Body where there is least Motion, that is, upon the extreme Superficies.