Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/269

 p o i

P o i

PoinT, in the manege. A horfe is faid to mzke z psint, when ii working upon volts, he does not ohferve the round regularly but pulling a little out of his ordinary ground, makes a fori of angle or point by his circular tread This fault is prevent- ed by haftening the hand. See Hasten.

Poivt is alfo ufed to denote the toes of a bow of af-iddie. See the article Bow.

POISON (Cyd)-We are apt to extend the fignification of this word very far, our common acceptation of it taking in every tiling which, taken into the body, is capable of deftroy- ing or highly injuring it. Hence the number of poifns is ereatlv increafed upon the world, and the ahufe of many things, naturally wholefome or ufeful in food or phyfic, brings them into the clafs of hurtful things. This, however, brings great confufion into the writings or difcourfe of fuch who ufe it; and the fenfe of the word poifon becomes very vi:gue and un- certain from it. A draught of cold water drank by a perfon ■while very hot, has been known to caufe inftant death; and according to this rule, cold water fhould therefore be a foifon.

Poifons are diftinguifhed by fome authors by feveral names, according to the different time and manner of their taking effect.

Some are called ve.nena terminate. Thefe are fuch poifns as perform their fatal office, according to the opinion of the world, at certain ftated or determinate periods of time: thus, according to the quantity given, or the nature of the fpecies of pnfon, a : man muft be killed by it at the pleafure of the giver, either in an hour, a day, a week, a month, many months, or years; the poifon in this laft cafe operating like a chronical difeafe, and carrying off the patient by a very tedious train of fymptoms.

Others are called venena temporanea, temporary poifons. Thefe will kill a man by degrees, every minute of his life growing worfe and worfe, from the time of taking them to the final period ; but this is not at any fluted or certain time. Others are called ddibntoria venena. Thefe are fuch as kill without being taken internally, and are furely fatal if rubbed upon the fkin, put into gloves, or the like. As to the firft of thefe kinds, it is very much to be doubted whether there be in nature any fuch thing as a venenum termi- natum, or a poifon which {hall kill at the fixed time at which the giver pleafes ; fmce all the known pcifrns are only relative- ly fuch, and depend for their effect on the peculiar ftate of the body : the different conftitutions of men muft therefore vary the period of time at which death muft happen from the tak- ing the fame dofe. At leaft, if it be poffible to contrive a terminatory poifon, it muft require the fkill of the ableft phy- fician to prepare it, fmce he muft at once know the true ftate of the perfon's body who is to take it, and the exact power of the poifon, in its feveral dofes, on other bodies. Much, therefore, is required in the pbyfician who is to cure a perfon who has fwallowed pofon; mice the nature of the medicine, and the true knowledge of the ftate of the patient's body, are both neceffary in order to know what fymptoms to expe.ll and guard againft.

Of the number of thofe poifons which take a long time to kill, and that different, according to their dofe and the habit of the perfon, are the venom of the toad and of the mad dog, whether the faliva be communicated immediately to the blood by a wound, or fwallowed with food or with the fpittle. The poifn of the tarantula is alfo of this number ; and to thefe may be added, that of the fmall pox, meafles, and other dif- eafes of that kind, which is evidently long dormant in the body, till certain peculiar occafions and accidents call it forth to appear in its proper form. The pnfon of the hectic fever Is alfo by fome referred to this, it being accounted an alkaline

' virus, mixed with a vifcid matter. The poifon of the French pox, lues venerea, is alfo of this kind, and is efteemed highly acrid and alkaline. The poifon of cantharides, the acid ones of nitre, fait, vitriol, fulphur; the folutions or cryftals of gold, lilver, and the other metals ; and the precipitates of mercury, and the very fatal common arfenic. To thefe are added many others, and among them fome which act merely mechanically, by their numerous fliarp points andedg:s; fuch as the powder of diamonds, glafs, and the like: and to this clafs belong many of the <\z\'\bulory pcifons. Stentzel Toxicolog. Of the temporaneous poijous many are taken under the com mon denominations of food and drink, and feem at firft to be of no injury; but by degrees they impair the constitution, and bring on difcafes and death. Coffee, Tea, and all the fpintu- ous liquors are accounted of this kind.

y t e'may perhaps afcribe the prodigious multiplicity of pofons, and that equallj numerous tribe of antidotes treated of by the amients, to the love of the marvellous: however, it cannot be denied', that fome things are very fuddenly and ftrangely deftructive to animal life, and that in very fmall quantities Among the reft, there is a poifon made ufe of by the Indians, fome of which was fent over to the royal fociety by Mr. de la Condamine: Di Brocklcfby has given us fome accounts of its effects on cats, dogs, and bird.-, who were foon killed by it, only by fprinkling a few drops of the folution of this p J fo?; on wounds made by a lancet. The doctor gave alfo two drachms of fugar to a bird, and fhortly afterwards poured a

little of the folution into its mouth ; but two drops had fcarce touched its tongue, before the cre.iture was convuifed, and could with difficulty be laid down before all motion was taken away.

Hence it appears, that fugar is no fpecific againft this poifon, even when only taken at the mouth. Phil. Tranf. N'-'! 4.821 Sea. 12. h

The negroes ufe a poifn of an extraordinary nature. The dofe is very fmall, and it hath no ill tafte ; fo that, mixed with meat or drink, it is not perceivable. It caufes divers fymptoms, and the effects are various, according as the dofe is large or fmall. It kills fometimes in very few hours, fome- times, it is faid, in fome months, and at others in fome years. 1 he fymptoms are according to the quantity given ; if great, it caufes evacuations upwards and downwards ; of excrements firft, then of humours, and laftly of blood with fainting fits and fweatings. Death follows in fix or feven hours. The negroes turn white. Phil. Tranf. N°. 462. p 3. The antidote to this poifn is the root of the fenfible weed, as it is commonly called, or hefba fenfitiva, in decoction. Id. ibid, p 4. Vegetable Poisons. It has been a general complaint, and indeed too juft a one, that the qualities of plants are much lefs ftudied than their external appearances ; and the beft modern authors have contented themfelves with nicely cha raft eri fin g plants ac- cording to their flowers and feeds, and afcertaining the proper names to each, without at all enquiring how they might be beneficial or hurtful to mankind, or dlftinguiihing whether they were fafe medicines or deftructive poifns. Nor, indeed, is the inveftigating the virtues of plants, yet untried as medi- cines, anyeafytafk; fince neither chemical analyfes, nor ex- periments on brutes, nor even the tafte and fmell, and other fenfible qualities of plant?, can ever certainly affure us what effects they will have on the human body. Chemical analyfes alter the fubftance too much to give any certain knowledge; and the effects things have on one animal are no affurance of what they will do to another, as is familiar to us in a thousand inftances. Bitter almonds, and many other things, wholly harmlefs to us, kill birds ; and goats will eat the tithymals, to give them an appetite when they want it, while thofe very plants are fatal to fifties, and very danger- ous to man. The fenfible qualities as often deceive us, of which we fhall give many inftances ; and what fome have ob- ferved of the botanical characters of plants, telling us their virtues, or that all of the fame clafs poffefs the fame qualities, is the moft erroneous, and, if trufted to, might prove the moffc fatal of all opinions; fmce the known poifons, hemlock, phel- landrium, and water-drop wort, with the poijlmus juice, are all umbelliferous plants, and confequently of the fame family with fennel and angelica.

Nothing can, indeed, allure us with any degree of certainty of the virtues of plants, but experiments made on ourfelves ; but few are to be found who wifti fo well to the public, as to venture their own lives for its fervice : and perhaps the honeft Gefner is the only man who ever carried thefe attempts to any degree, and he unhappily died a martyr to them, perifbintf by the dofe he took of the fcorpion-rooted doronicum ; the very root which has of late with us been fo fatal, by being acci- dentally mixed with our gentian.

What we learn of the vegetable/w/o.-?j muft therefore be either by the confequences of the rath prefcriptions or miftakes of the ignorant pretenders to medicine, or by the misfortune of thofe who have unwarily eaten them.

We have accounts in the memoirs of the academy of fciences of Paris, of many things of this kind. An apothecary, a very honeft man, but of no knowledge in botany, had made his extract of black hellebore from the roots of the chriftophoriana, or bane-berries, a plant always accounted a poifon, and a fmgle berry of which is capable of killing feveral animals ; yet fo far had the fire diverted the roots of their pcifonous qualities, that twelve grains of this given as extract of hellebore, proved of no ill effect. Mem. Acad. Scienc. Par. 1739. Another apothecary having learned, that hermodactyls were the roots of a fpecies of colchicum, dried the roots of the com- mon colchicum, and fold them in its place; yet there is no knowledge of any ill effects from them.

The enquiiy into things of this kind has its ufe, and tiut no fmall one; fince poifons often differ only in dofe from medi- cines, and many of the vegetables effeemed poifonous, may perhaps be found ufeful remedies, with proper management and in proper quantities.

The lauR-1-leaves are well known to afford ?>. poifonous water in diftillation, yet it is as well known that they have been long ufed in cookery, to give a tafte like that of bitter almonds to creams &e. and that without any ill effect. The rofe-bay, or oleander, is well known to be a pdjen to goats, yet i' taken by the country-men of ffrongand robuft habits as a purge, and that with very good fijecefs. Nay, opium, one of the greateft of all medicines, if it had firft been difcovercd by perfons taking over-dofes of it, and dying by it, as they naturally muft have done, might very naturally have been recorded to us as a very fatal p-ifm.

The plumbago, or dcntillaria of Rondeletius, is fo violent a

cauftie, that a poor girl who once anointed herfelf with it, to

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