Skip to main content

Full text of "Medical Jurisprudence And Toxicology"

See other formats

CHEMICAL  ANALYSIS                                                  447

Wet Method.—This consists in oxidizing the organic matter by thoroughly
wetting in a Kjeldahl flask about 25 grammes ot the third portion of the
original mixture with about 15 cc. of dilute nitric acid possessing a specific
gravity of 1.25 or containing 40 per cent by weight of nitric acid and heating
the flask for a few minutes. It is cooled and about 20 cc. of concentrated
sulphuric acid are added. The mixture is again heated and concentrated
nitric acid is dropped in from a specially prepared dropping funnel at the
rate of 10 to 15 drops a minute till the occurrence of complete oxidation
which is indicated by the absence of charring on further heating without the
addition of nitric acid. The atmosphere in the flask must at no time be free
from red fumes. When all the organic matter is destroyed, the addition of
nitric acid is stopped, and the heating is carried on till the red fumes are no
longer seen. After cooling, 40 cc. of water and 25 cc. of a saturated solution
of chemically pure ammonium oxalate are added and the whole mixture is
boiled and reduced to a small bulk by the decomposition of excess of
sulphuric acid as indicated by white fumes of sulphur trioxide. The solution
is then ready for estimation of metals, such as lead, arsenic, copper, zinc,
manganese, etc. which may be tested by the grouping reagents and confir-
matory tests.13

Dry Method.—The organic matter in the mixture is destroyed by heat
so as to incinerate it completely. To the ashes thus obtained add strong
nitric acid. The excess of the free acid should be removed by heat, and the
nitrate should be dissolved in water and tested in the usual way. If the
mixture is strongly acid in reaction, caustic potash may be adfled to
neutralize it.


Domestic animals may be fed with the suspected food, or with the poison
after it is separated from the viscera and the symptoms exhibited by them
should be noted. However, the evidence derived in this manner cannot be
relied on in all cases, as some symptoms, such as vomiting, etc. may be pro-
duced without any poison, and some animals may not be affected even by
poisons. For example, rabbits are insusceptible to the leaves of belladonna,
hyoseyamus and stramonium ; so are pigeons to- opium. BujMbhejgaJLaiid the
dog are affected/bYJQoisonsalmost injhe'same way as man.


In a case of criminal poisoning the fact whether' the accused was the
person who administered the poison can be proved only from moral and
circumstantial evidence.   This is furnished by common witnesses, who testify
to the recent purchase erf the poison by the accused,  etc.   The medical
witness should not hazard an opinion on moral and circumstantial proof.
He should certify to the cause of death from medical facts only.   He should V-
not, however, omit to note the stmmmdmgs of the patient, and the nervo*is- |
ness and anxiety of the relatives or some other persons regarding the haste
with which they want Urn body to "be disposed of by burial or cremation.        l


A me<fical practitioner must "be very cautious in giving his opinion about
poisoning.   On mere suspicion he should never give a verbal or
opinion lest he be the victim of an action for damages brqygfa^

In a sn^lciatis case dF acute pd&pttg tibe medical

13.   Blamberg, Ana^/st^ ' VotHft*F. &