822 
P O I 
Sal Ammoniac, placed upon live coals, is volatilized, 
and gives a white vapour; triturated with quick-lime, 
it exhales the odour of volatile alkali ; diffolvedin water, 
and mixed with nitrate of filver, it occafions a heavy 
white precipitate. 
Liver of Sulphur is folid, of a greenifh-yellow colour; 
mixed with vinegar and water, it difengages an infupport- 
able odour like rotten eggs. 
All the preparations of Barytes mixed with well-water 
or water having Glauber’s or Epfom falts in folution, 
give a white precipitate, which is infoluble in water or 
diluted nitric acid. Sulphate of foda (Glauber’s fait) 
effects no fuch change in thefe fluids ; it is therefore im- 
poflible to confound them. Pure barytes diflolved in 
water changes fyrup of violets green. The carbonate of 
barytes, which is the ufual form in which it is employed 
as a poifon for rats, is bell difcovered by diflolving it in 
muriatic acid, and adding fulphuric acid, or fulphate of 
foda, which produce an infoluble precipitate. 
The pow'der of Cantharides, even when it has palled 
through a filk lieve, is of a mixed colour of green and 
grey, and offers many points of a fine green. It has an 
acrid and naufeous odour; placed upon hot coals it 
throws offa fetid odour fimilar to burnt horn, and leaves 
a portion of charcoal as refidue. 
Preparations of Lead, heated to rednefs with potafh 
and charcoal, are decompofed and reduced to a metallic 
ftate. A folution is known to contain lead, i. by the 
liquid having a fugary talle; a. by adding fulphuric acid, 
which caufes a white precipitate; 3. by fulphuretted hy¬ 
drogen, which produces a black depofit. “ In order to 
apply this teft, add to a portion of the fufpe&ed liquor, 
about halt its bulk of water impregnated witli fulphuretted 
hydrogen gas. If lead be prefent, it will be manifefted by 
a dark brown or blackilh tinge. This tell is fo delicate, 
that: water condenfed by the leaden worm of a ftill-tub is 
fenfibly affedled by it. It is alfo detedled by a fimilar 
effedl enfuing on the addition of fulphuret of ammonia, 
or potafh.” Henry’s Chemiftry. 
As chemiftry furnifhes no diftinguifhing marks of vege¬ 
table poifons, it is the more neceffary that we fliould 
know accurately the external appearances of poifonous 
plants. We believe the defcriptions and plates contained 
in this work, under the various botanical articles, will 
be found excellent affiftants in this talk. We may juft 
add, that plants whole flowers have five ftamens, one 
piftil, one petal,and whofe fruit is of the berry kind, may 
at once be pronounced as poifonous; that the umbellife¬ 
rous plants which grow in water are moftly poifonous ; 
and that fuch as have the corolla purple and yellow may 
be fufpedled of being fo. 
Having detailed the means of curing thofe who are 
poifoned, if curable, or of finding the nature of the poifon 
taken; it remains only that we fliould make a few fhort 
remarks as to the evidence touching this matter which 
a medical practitioner may be called on to give in a court 
ofjuftice. Of courfe, if poifonous fubftances be adlually 
found in the ftomach of a man, the evidence is eafily 
given ; but it is proper to be known, that cafes have been 
recorded where no poifon could be found in the ftomach 
after a few hours, though it was certain it had been ad- 
miniftered. He/e, therefore, we have only the appearances 
on diffedfion to guide us: and here it fliould be remem¬ 
bered, that ulceration and erofion are fometimes the 
eftedts of difeafe; and that the opinion of John Hunter, 
that the gaftric juice may in fome inftances diffolve the 
ftomach after death, is worthy of attention. It is only, 
therefore, when the fymptoms in their nature and quick- 
nej's accord with thefe appearances, that a furgeon can 
inform a jury that it is probable poifon has been given. 
Yet, when thefe fymptoms are, from the fmallnefs of the 
dofe, neither fudden or marked, nor the morbid appear¬ 
ances on difledlion clearly manifefted, ftill he may fpeak 
as to the poffibility of the crime having been committed. 
It is true, the circumftances of the cafe might decide; 
SON. 
but the medical evidence has nothing to do with this; 
he mull give his country the indications from his pro- 
feftional knowledge, ur.biaffed by any circumftances. 
Nor mull he ever temper juftice with mercy, feeing that 
mercy refts not with him, but with the jury and the king; 
for, if this benignant maxim is to be followed by an evi¬ 
dence, the mercy will become fo preponderant as to fritter 
away the juftice altogether. We mention this, becaufe we 
fear the -philanthropic difpofition of the profeflion often 
leads them into this error. It need fcarcely be obferved, 
that, fliould any unexpefted or contradictory circum- 
llance attend the analyfis of the poifon, this fliould be 
frankly ftated. The fwelling of the body which takes 
place after death, fometimes is no caufe for fufpefling 
that poifon has been taken. 
This is not exactly the place to treat of the flow adtion 
ofpoifons; nor indeed has a fufficient number of obfer- 
vations been made to furnifli a complete hiftory of the 
fubjeft. It is proper to obferve however, that, as arfenic, 
mercury, digitalis, and opium, are in common ufe as me¬ 
dicines, and as each of them has a flow and-deleterious 
influence on the body, in particular circumftances, as 
formidable as their more rapid aflion, it behoves medical 
pradlitioners to adminifter them only when abfolutely 
called for, to watch their influence with care, and to make 
themfelves as well acquainted as poffiblewith their modus 
operandi. That excellent medicine arfenic, continued 
long in minute dofes, diiorders very materially the ftruc- 
ture of the (kin, and evinces, by tremblings and giddinefs, 
an alteration in the brain by no means free from danger. 
The morbid efl’e&s which refult from the abufe of mer¬ 
curial preparations are well known. It is ufeful to recoi¬ 
led!, however, that expofure to cold, and likewife an in¬ 
temperate life, are as frequently the caufe of mercurial 
difeafes as the improper adminiftration of this medicine. 
Opium keeps up an undue adlion of the brain, and re- 
ftrains many of the fecretions. But digitalis, we have 
ftrong reafon to fuppofe, produces more deaths by its 
mal-adminiftration than all the reft of the materia medica, 
excepting perhaps the new medicine, iodine. It has fallen 
to our lot to witnefs many cafes of death in children 
which we could trace to no other caufe than the exceflive 
exhibition of digitalis. The fymptoms being chiefly (uch 
as regard the pulfe, manifeft finking and intermittence 
are remarked ; the patient dies ; and a congefted ftate 
of the mucous membrane is met with on examination. 
Iodine is faid alfo to be a very dangerous remedy taken 
internally, though very fafe as an external application. 
Phyficians are not, however, agreed as to the fpecific ef- 
fedfs of this medicine : fome fay it injures by its exciting 
qualities, others by its fedative aflion. 
Our anceftors had fome abfurd fears of flow poifons; 
and accordingly many exaggerated ftories on the fubje£l 
pafied current among them. The account of the Aqua 
Tofana, fo called from its fuppofed inventrefs, is amu- 
fing. This poifonous liquor was ufed to a very great 
extent at Naples and Rome during the latter half of the 
feventeenth century. Gmelin fays, that more people 
were deftroyed by it than by the plague which had pre¬ 
vailed a fhort time before it came into ufe ; and Garelli, 
chief phyfician to the emperor, wrote to Hoffmann, that 
Tofana confeffed file had ufed it to poifon more than fix 
hundred perfons. It is to be regretted, that Garelli has 
not given us fome details of the infamous Tofana; as the 
little that we know of her refts upon the authority of 
travellers, and is evidently exaggerated, and lometimes 
irreconcilable with eftabliflied tails. She was a Sicilian 
by birth, and refided firft at Palermo, and then at Naples. 
She was extremely liberal of her preparation, chiefly, it is 
faid, to ladies tired of their hufbands ; and, the better to 
conceal the nature of her gift, it was put up in fmall flat 
phials, infcribed Manna of St. Nicholas of Bari, ornament¬ 
ed on one fide with an image of the faint, that it might 
pafs for a l’quid faid to drop from his tomb at Bari, which 
was in great requeft, on account of the medicinal virtues 
afcribed 
a 
