Nor is it perhaps amiss to remark, that in _Maniacal_ People, as is frequently observ’d, a Quadruple Dose of _Opium_ will scarce produce any considerable Effect: Now in Persons so affected, the Mind is deeply ingaged and taken up with some _Images_ or other, as Love, Anger, _&c._ so that it is not to be so easily moved or diverted by those pleasing Representations which it would attend to at another time, and upon which the Virtues of this Medicine do in a great measure depend. Besides this, those who are _Maniacal_ do to a Wonder bear the Injuries of Cold, Hunger, _&c._ and have a prodigious degree of Muscular Force, which argues the Texture of their _Blood_ to be very strong, and the Cohæsion of its _Globules_ great; so that the Spirituous Parts of the _Opiate_ cannot make that Disjunction and Rarefaction of this Fluid in Them, which it does in ordinary Bodies and Constitutions. Many are the Immprovements which might be made of this Theory, with relation to the Practice of Physick; but these will be obvious enough to one instructed in the Animal _Œconomy_. To conclude then as to the Subject in Hand, it is very plain that there needs no more to make _Opium_ prove Destructive or a _Poison_, than to take too great a quantity of It; for then It must Inflame the Stomach, and Rarefie the Blood to such a Degree, that the Vessels cannot again recover their Tone, whereupon Apoplectic Symptoms, _&c._ will insue. To be convinced of this, I forced into the Stomach of a small Dog about half a Drachm of Crude _Opium_ dissolved in Boiling Water. He quickly Vomited It up with a great quantity of Frothy Spittle; but repeating the Trial, by holding up his Head, and beating him, I made him retain Three or Four Doses, intermitting between each about a quarter of an Hour; when he had thus taken, as I could guess, near Two Drachms, I watch’d him about an Hour, then he began to Sleep, but presently started up with Convulsions, fell into universal Tremblings, his Head constantly twitch’d and shaking, he breath’d short and with labour, lost intirely the Use first of his hinder Legs, and then of the fore ones, which were stiff and rigid like Sticks. As he lay Snorting, to hasten his End, I was giving him more of the Solution, but on a sudden his Limbs grew limber, and He Died. Opening his _Stomach_, I found It wonderfully distended, tho’ empty of every thing but some Water and _Opium_; parcels of Frothy _Mucus_ swimming in It; the inside was as clean as if scraped and washed from all the Slime of the Glands, with some Redness here and there, as in a beginning Inflammation. The _Pylorus_ was Contracted. The Blood-Vessels of the Brain were very full; and I took out a large Grume of Concrete Blood from the upper part of It, cutting into the _Sinus Longitudinalis_, as is not uncommon in Apoplectic Carcasses; but found no extravasated _Serum_ in the _Ventricles_, nor among any of the Membranes.