Heh I wouldn't rely TOO much on old, old medicine. Even as late as the 1700s (I have some antique medical books, titled 'the household physician' intended both for the doctor and the domestic layman needing advice, big, heavy, leather-bound tomes, with the first pages as well as the edges of each page (that is, the edges at the thinnest axis, so the effect can be seen only when the book is closed or a large section of pages are closed) are ink-marbled. And uniquely, my copies have many little slips of old paper bearing handwritten notes in elegant, cursive script each bearing a recipe for a personal concoction of a remedy, with the name of the mixture, the purpose of its use, ingredients and in what quantities and proportions and dosage, and how to use them)
Even then, they were still using things like blue pill ( a mercury based concoction as a purgative), grey mass. which is no more than mercury metal bashed up with chalk to a paste, resulting in a more absorbable form of Hg metal due to its being very finely divided due to the effect of being pounded up with chalk, this was used for teething in babies amongst other problems), many many other mercury compounds (internally, calomel was used, for a lot of things, even in babies and the very young child, calomel being a very old name for the monovalent chloride of mercury (Hg forms two chlorides, Hg (I) chloride, HgCl, and HgCl2, the divalent chloride (Hg (II) chloride) or to give it the old fashioned name, 'corrosive sublimate', which is extremely toxic [mercury (I) salts, that is, where the mercury is in the (I) oxidation state, rather than the mercuric [Hg (II) oxidation state) are less toxic compared to mercuric salts which are vastly more poisonous. I use, very rarely, mercuric chloride, HgCl2, the divalent chloride, for amalgam reductions, but I am prepared to go to considerable expense if needs be to employ other reagent systems just to avoid handling or using mercuric salts, owing to how extremely poisonous they are. In fact, bar just a handful of things I've used or do use, such as cyanides, HgCl2 is likely one of the most lethally toxic substances present on or in any of my reagent shelves or cupboards, and so much so that I keep my HgCl2 not just in the container it came in, tightly closed, but that container is inside a sealed bag, which is itself inside another bag in a bag. And it gives me a case of the nervous willies just opening the door of the closed cupboard the mercuric chloride (just a single gram, or at least, that was how much was inside the container when it was originally purchased, there is of course less now, due to some having been used)
But its deadly toxic, cumulatively poisonous in quantities that are not lethal in a single exposure, it can be absorbed through unbroken skin and it is also volatile, making it dangerous in terms of vapor liberation, especially in hot conditions, such as amalgam reductions which can get hot enough to boil the solvent, and quickly, for these reactions I ALWAYS pipe the vapor away and preferably recondense it, and have the exit pipe situated on the end of a stack of my most efficent condensers that quite literally, has JUST enough space for the exit tubing, a matter of perhaps 3 inches short of the condenser's end furthest away from the reaction flask touching the ceiling. I've used such reactions a bare handful of times, don't like them for every possible reason either. They are an abomination to extract product from, they scale up terribly due to the extremely exothermic nature of the reaction (can boil in moments if its anything but a small reaction on 10-15g substrate at most), the mercury is bastardly toxic, I have to use sulfur in the form of 'flowers of sulfur', an old, but rather nice name for very pure, resublimed sulfur in the form of extremely fine dust) all over the lab bench, I puff it from a container with a seal over the top with a small hole in the top of the seal, so as to emit a puff of sulfur dust as a cloud when the container is quickly squeezed, then relaxed for another cloud of sulfur dust to be puffed out. This goes EVERYWHERE Hg vapor or the vapor of its salts could conceivably go to, because mercury and its compounds have a vast affinity for sulfur (the name for the sulfur analogs of alcohols, now known often as thiols, has an older synonym, 'mercaptans', coming from the latin 'mercurium captans', to capture mercury. Indeed mercury exerts a lot of its toxicity by binding to sulfur-containing aminoacids such as cysteine and methionine which are vital in proteins, and buggering up the structure of the proteins, such as by inhibiting the formation of disulfide bonds and distrupting the protein)
Right now, feeling a few things-missing chemistry in practice, been able to get around on my feet recently only with great pain, being stiff, sore, and with limited movement and mobility, although it seems to be beginning to recover. And I want BADLY to get back to my flasks and my bottles, gauges, valves, test tubes, pumps etc.
Only plus side is that it has allowed me to save up money for the purpose of buying a reagent which is very expensive but which would make my life a LOT easier.
Back though to old school medicine circa 1700s, as cited in my old tomes of delightful ancient and by now utterly arcane and superseded knowledge. Mercury in many preparations, as were its salts, were used, in both adults and children and babies even. Arsenical drugs were used (actually arsenic IS still used, for certain highly specific purposes, related to certain cancers. It is in last year or the year before of the BNF, british national formulary, our list of prescribable or usable medicaments within the british isles, at least england, ireland, scotland and wales; (can't check up which year exactly because my copy of the BNF happened to be at one point situated near a chemical synthesis involving phosphorus triiodide, generated in-situ and there was a rather large plume of hydrolyzed PI3 vapor at one point escaping from the pressure-vessel being used, and the book got iodinated to buggerdom, staining the front cover to hell and back, along with milder staining although readable in many other areas:autism: (no, not making meth, I've better methods than buggering around going to the effort of extracting pseudoephedrine/ephedrine from OTC products or growing ephedra plants and extracting from them, if I wished to produce meth, I just, well, have many ways to deprive that particular felid of its outermost wrapper)
However it IS certainly from the last year or two, and one of the simple arsenic compounds, IIRC either one of the arsenical acids or arsenic trioxide are in the book, indicated for cancer treatment, only available through hospitals under the use of a cancer specialist; it IS in there though.
In the old school books I have, though, mercury aplenty, arsenic in many forms, white phosphorus (it is highly, highly toxic, a little less so perhaps or about equally as poisonous as cyanide), indeed, hydrocyanic acid (hydrogen cyanide gas in aqueous solution, in several strengths used to be used IIRC for 'nervous irritability', nitric acid used to be used as an external wash applied to varicose anal veins (piles) (!!!!!!!! or what? !!!) Sheeesh!, antimony was used as an emetic (a poisonous semimetal related to arsenic, phosphorus, bismuth and nitrogen, although of course nitrogen isn't toxic, phosphorus is only toxic in certain forms, at least in the case of the element itself, as the white allotropic forms (of which there are more than one, differing in physical structure, cubic, monoclinic etc, vapor as P2 rather than P4 tetrahedra in the solid forms of the white allotrope)
And plant poisons like strychnine were used in small doses as a stimulant and tonic, aconitine (from the aconite plant, commonly known as monkshoods, and one of several plants, this genus being the most commonly termed so, named 'wolfbane', so poisonous that it is one of perhaps three plants that can vye for top place as THE most lethal plant in great britain (not including foreign territories like gibraltar etc) or the falkland isles and what have you), Aconite the plant itself can be lethally poisonous just by contact of the juice of the plant with unbroken skin, even simply handling the plant without gloves for a time, can be enough to cause toxic symptoms affecting the heart although simply brushing against it is unlikely to do so. A single leaf, internally could well prove fatal.
Hellebores (I mean, here, Veratrum species, the green or white false hellebores, as opposed to the 'true' hellebore, black hellebore the christmas rose) were used to provoke sneezing as a snuff to cure or relieve catarrrh although it is so poisonous a tiny slice of a stem could kill if swallowed, and also Conium, the common hemlock (there are a few other plants known as hemlocks, true hemlock, Conium maculatum, one of the umbellifers, related to carrot, hogweeds, cow parsely and anise, typically have hollow, green fleshy stems, some have strong smells, and they generally have large fleshy roots, like carrot, parsnip etc. The other two toxic plants called hemlock, or at least the truly lethal ones, are the water hemlocks, Oenanthe (several species, O.crocata being the most common and probably the most lethal Oenanthe species) whilst the other water hemlock is Cicuta, C.virosa in particular. Both contain long-chain linear polyhydric (having multiple hydroxyl groups) alcohols, which feature in cicutoxin, as well as the similar oenanthetoxin from O.crocata and several but not all Oenanthe species, as well as carotatoxin, of similar structure and found in the carrot plant, chiefly in the roots. However it is present in tiny quantities. And there is also the hemlock tree, one of the coniferous trees, which has nothing in common with the water hemlocks, nor with Conium.
There are major differences in Conium, the active principle here is a paralytic agent, whereas cicutoxin from Cicuta spp. and oenanthetoxin from Oenanthe, as well as carotatoxin, these are convulsants and terror-inducing panicogen agents, which cause a truly agonizing, horrible death, the sort of thing you'd reserve for unleashing on paedophile rapist-killers and those guilty of the most heinous acts of animal cruelty, as well as islamoverminous radical filth. Ironically despite the utter, abject agonizing horror of the way these kill, leaves the victim with a rictus grin of a smile on their faces due to the convulsant properties sending the oral muscles into a death-spasm.
Nasty, nasty REALLY fucking nasty way to go. These, afaik weren't used medicinally. Too unpleasant and too lethal (a single bite of a single leaf, or single bite of root is enough to kill a full grown cow) whilst Conium, was used to sedate the nerves applied locally and used in an ointment, with great care, for trigeminal neuralgia and other neuralgias. Coniine, the active paralytic principle is IIRC structurally related to nicotine, albeit with an inverse action compared to nicotine. This plant, Conium maculatum ('maculatum' means 'spotted', forget if its in greek or latin) but Conium hemlock was the poison used to execute the greek philosopher Socrates when he was convicted of impiety towards the greek gods, for those of interest in history)
