PART II._Poisons, Their Effects and Detection A Manual for the Use of Analytical Chemists and Experts

I.--Definition of Poison.

§ 14. The term “_Poison_” may be considered first in its legal, as

distinct from its scientific, aspect.

_The legal definition_ of “poison” is to be gathered from the various

statute-books of civilised nations.

The English law enacts that: “Whoever shall administer, or cause to be

administered to, or taken by any person, any poison or other destructive

thing, with intent to commit murder, shall be guilty of felony.”

Further, by the Criminal Consolidation Act, 1861: “Whosoever shall, by

any other means other than those specified in any of the preceding

sections of this Act, attempt to commit murder, shall be guilty of

felony.”

It is therefore evident that, by implication, the English law defines a

poison to be a destructive thing administered to, or taken by, a person,

and it must necessarily include, not only poisons which act on account

of their inherent chemical and other properties after absorption into

the blood, but mechanical irritants, and also specifically-tainted

fluids. Should, for example, a person give to another milk, or other

fluid, knowing, at the same time, that such fluid is contaminated by the

specific poison of scarlet fever, typhoid, or any serious malady capable

of being thus conveyed, I believe that such an offence could be brought

under the first of the sections quoted. In fine, the words “_destructive

thing_” are widely applicable, and may be extended to any substance,

gaseous, liquid, or solid, living or dead, which, if capable at all of

being taken within the body, may injure or destroy life. According to

this view, the legal idea of “poison” would include such matters as

boiling water, molten lead, specifically-infected fluids, the flesh of

animals dying of diseases which may be communicable to man, powdered

glass, diamond dust, &c. Evidence must, however, be given of guilty

intent.

The words, “administered to or taken by,” imply obviously that the

framers of the older statute considered the mouth as the only portal of

entrance for criminal poisoning, but the present law effectually guards

against any attempt to commit murder, no matter by what means. There is

thus ample provision for all the strange ways by which poison has been

introduced into the system, whether it be by the ear, nose, brain,

rectum, vagina, or any other conceivable way, so that, to borrow the

words of Mr. Greaves (_Notes on Criminal Law Consolidation_), “the

malicious may rest satisfied that every attempt to murder which their

perverted ingenuity may devise, or their fiendish malignity suggest,

will fall within some clause of this Act, and may be visited with penal

servitude for life.”

Since poison is often exhibited, not for the purpose of taking life, but

from various motives, and to accomplish various ends--as, for example,

to narcotise the robber’s victim (this especially in the East), to quiet

children, to create love in the opposite sex (love philters), to detect

the secret sipper by suitably preparing the wine, to expel the

inconvenient fruit of illicit affection, to cure inebriety by polluting

the drunkard’s drink with antimony, and, finally, to satisfy an aimless

spirit of mere wantonness and wickedness, the English law enacts “that

whosoever shall unlawfully or maliciously administer to, or cause to be

taken by, any other person, any poison or other destructive or noxious

thing, so as thereby to endanger the life of such person, or so as

thereby to inflict upon such person any grievous bodily harm, shall be

guilty of felony.”

There is also a special provision, framed, evidently, with reference to

volatile and stupefying poisons, such as chloroform, tetrachloride of

carbon, &c.:--

“Whoever shall unlawfully apply, or administer to, or cause to be taken

by any person, any chloroform, laudanum, or other stupefying or

overpowering drug, matter, or thing, with intent, in any such case,

thereby to enable himself or any other person to commit, or with intent,

&c., to assist any other person in committing, any indictable offence,

shall be guilty of felony.”

§ 15. The German statute, as with successive amendments it now stands,

enacts as follows:[27]--

[27] “Wer vorsätzlich einem Andern, um dessen Gesundheit zu beschädigen,

Gift oder andere Stoffe beibringt, welche die Gesundheit zu zerstören

geeignet sind, wird mit Zuchthaus von zwei bis zu zehn Jahren bestraft.

“Ist durch die Handlung eine schwere Körperverletzung verursacht worden,

so ist auf Zuchthaus nicht unter fünf Jahren, und wenn durch die

Handlung der Tod verursacht worden, auf Zuchthaus nicht unter zehn

Jahren oder auf lebenslängliches Zuchthaus zu erkennen.

“Ist die vorsätzliche rechtswidrige Handlung des Gift--&c.,--Beibringens

auf das ‘Tödten’ gerichtet, soll also durch dieselbe gewollter Weise der

Tod eines Anderen herbeigeführt werden, so kommt in betracht: Wer

vorsätzlich einen Menschen tödtet, wird, wenn er die Tödtung mit

Ueberlegung ausgeführt hat, wegen Mordes mit dem Tode bestraft.”

“Whoever wilfully administers (_beibringt_) to a person, for the purpose

of injuring health, poison, or any other substance having the property

of injuring health, will be punished by from two to ten years’

imprisonment.

“If by such act a serious bodily injury is caused, the imprisonment is

not to be less than five years; if death is the result, the imprisonment

is to be not under ten years or for life.

“If the death is wilfully caused by poison, it comes under the general

law: ‘Whoever wilfully kills a man, and if the killing is premeditated,

is on account of murder punishable with death.’”

The French law runs thus (Art. 301, _Penal Code_):--“Every attempt on

the life of a person, by the effect of substances which may cause death,

more or less suddenly, in whatever manner these substances may have been

employed or administered, and whatever may have been the results, is

called poisoning.”[28]

[28] “Est qualifié _empoisonnement_--tout attentat à la vie d’une

personne par l’effet de substances qui peuvent donner la mort plus ou

moins promptement, de quelque manière que ces substances aient été

employées ou administrées, et quelles qu’en aient été les suites.”--Art.

301, _Penal Code_.

There is also a penalty provided against any one who “shall have

occasioned the illness or incapacity for personal work of another, by

the voluntary administration, in any manner whatever, of substances

which, without being of a nature to cause death, are injurious to

health.”[29]

[29] “Celui qui aura occasionné à autrui une maladie ou incapacité de

travail personnel en lui administrant volontairement, de quelque manière

que ce soit, des substances qui, sans être de nature à donner la mort,

sont nuisibles à la santé.”--Art. 317, _Penal Code_.

§ 16. =Scientific Definition of a Poison.=--A true scientific definition

of a poison must exclude all those substances which act

mechanically,--the physical influences of heat, light, and electricity;

and parasitic diseases, whether caused by the growth of fungus, or the

invasion of an organism by animal parasites, as, for example,

“trichinosis,” which are not, so far as we know, associated with any

poisonous product excreted by the parasite;--on the other hand, it is

now recognised that pathogenic micro-organisms develop poisons, and the

symptoms of all true infections are but the effects of “toxines.” The

definition of poison, in a scientific sense, should be broad enough to

comprehend not only the human race, but the dual world of life, both

animal and vegetable.

Husemann and Kobert are almost the only writers on poisons who have

attempted, with more or less success, to define poison by a

generalisation, keeping in view the exclusion of the matters enumerated.

Husemann says--“We define poisons as such inorganic, or organic

substances as are in part capable of artificial preparation, in part

existing, ready-formed, in the animal or vegetable kingdom, which,

without being able to reproduce themselves, through the chemical nature

of their molecules under certain conditions, change in the healthy

organism the form and general relationship of the organic parts, and,

through annihilation of organs, or destruction of their functions,

injure health, or, under certain conditions, destroy life.” Kobert

says:--“Poisons are organic or inorganic unorganised substances

originating in the organism itself, or introduced into the organism,

either artificially prepared, or ready formed in nature, which through

their chemical properties, under certain conditions, so influence the

organs of living beings, that the health of these beings is seriously

influenced temporarily or permanently.”

In the first edition of this work I made an attempt to define a poison

thus:--_A substance of definite chemical composition, whether mineral or

organic, may be called a poison, if it is capable of being taken into

any living organism, and causes, by its own inherent chemical nature,

impairment or destruction of function_. I prefer this definition to

Kobert’s, and believe that it fairly agrees with what we know of

poisons.

II.--Classification of Poisons.

§ 17. At some future time, with a more intimate knowledge of the way in

which each poison acts upon the various forms of animal and vegetable

life, it may be possible to give a truly scientific and philosophical

classification of poisons--one based neither upon symptoms, upon local

effects, nor upon chemical structure, but upon a collation and

comparison of all the properties of a poison, whether chemical,

physical, or physiological. No perfect systematic arrangement is at

present attainable: we are either compelled to omit all classification,

or else to arrange poisons with a view to practical utility merely.

From the latter point of view, an arrangement simply according to the

most prominent symptoms is a good one, and, without doubt, an assistance

to the medical man summoned in haste to a case of real or suspected

poisoning. Indeed, under such circumstances, a scheme somewhat similar

to the following, probably occurs to every one versed in toxicology:--

A. POISONS CAUSING DEATH IMMEDIATELY, OR IN A FEW MINUTES.

There are but few poisons which destroy life in a few minutes. Omitting

the strong mineral acids, carbon monoxide, carbon dioxide, with the

irrespirable gases,--_Prussic acid_, _the cyanides_, _oxalic acid_, and

occasionally _strychnine_, are the chief poisons coming under this head.

B. IRRITANT POISONS (symptoms mainly pain, vomiting, and purging).

_Arsenic_, _antimony_, _phosphorus_, _cantharides_, _savin_, _ergot_,

_digitalis_, _colchicum_, _zinc_, _mercury_, _lead_, _copper_, _silver_,

_iron_, _baryta_, _chrome_, _yew_, _laburnum_, _and putrid animal

substances._

C. IRRITANT AND NARCOTIC POISONS (symptoms those of an irritant nature,

with the addition of more or less pronounced cerebral indications).

To this class more especially belong _oxalic acid_ and _the oxalates_,

with several poisons belonging to the purely narcotic class, but which

produce occasionally irritant effects.

D. POISONS MORE ESPECIALLY AFFECTING THE NERVOUS SYSTEM.

1. NARCOTICS (chief symptom insensibility, which may be preceded by more

or less cerebral excitement): _Opium_, _Chloral_, _Chloroform_.

2. DELIRIANTS (delirium for the most part a prominent symptom):

_Belladonna_, _hyoscyamus_, _stramonium_, _with others of the

Solanaceæ_, to which may be added--_poisonous fungi_, _Indian hemp_,

_lolium temulentum_, _œnanthe crocata_, and _camphor_.

3. CONVULSIVES.--Almost every poison has been known to produce

convulsive effects, but the only true convulsive poisons are the

_alkaloids of the strychnos class_.

4. COMPLEX NERVOUS PHENOMENA: _Aconite_, _digitalis_, _hemlock_,

_calabar bean_, _tobacco_, _lobelia inflata_, and _curara_.

* * * * *

§ 18. KOBERT’S CLASSIFICATION.--The latest authority on

poisons--Kobert--has classified poisons according to the following

scheme:--

I. POISONS WHICH CAUSE COARSE ANATOMICAL CHANGES OF THE ORGANS.

A. Those which specially irritate the part to which they are

applied.

1. _Acids._

2. _Caustic alkalies._

3. _Caustic salts_, especially those of the heavy metals.

4. Locally irritating organic substances which neither can be

classified as corrosive acids nor alkalies, nor as corrosive salts;

such are:--_cantharidine_, _phrynine_, and others in the animal

kingdom, _croton oil_ and _savin_ in the vegetable kingdom. Locally

irritating colours, such as the _aniline dyes_.

5. Gases and vapours which cause local irritation when breathed,

such as _ammonia_, _chlorine_, _iodine_, _bromine_, and _sulphur

dioxide_.

B. Those which have but little effect locally, but change

anatomically other parts of the body; such as _lead_, _phosphorus_,

and others.

II. BLOOD POISONS.

1. Blood poisons interfering with the circulation in a purely

physical manner, such as _peroxide of hydrogen_, _ricine_, _abrine_.

2. Poisons which have the property of dissolving the red blood

corpuscle, such as the _saponins_.

3. Poisons which, with or without primary solution of the red blood

corpuscles, produce in the blood methæmoglobin; such as _potassic

chlorate_, _hydrazine_, _nitrobenzene_, _aniline_, _picric acid_,

_carbon disulphide_.

4. Poisons having a peculiar action on the colouring matter of the

blood, or on its decomposition products, such as _hydric sulphide_,

_hydric cyanide_, and the _cyanides_ and _carbon monoxide_.

III. POISONS WHICH KILL WITHOUT THE PRODUCTION OF COARSE ANATOMICAL

CHANGE.

1. Poisons affecting the cerebro-spinal system; such as

_chloroform_, _ether_, _nitrous oxide_, _alcohol_, _chloral_,

_cocaine_, _atropine_, _morphine_, _nicotine_, _coniine_,

_aconitine_, _strychnine_, _curarine_, and others.

2. Heart Poisons; such as, _digitalis_, _helleborin_, _muscarine_.

IV. POISONOUS PRODUCTS OF TISSUE CHANGE.

1. Poisonous albumin.

2. Poisons developed in food.

3. Auto-poisoning, _e.g._ uræmia, glycosuria, oxaluria.

4. The more important products of tissue change; such as, _fatty

acids_, _oxyacids_, _amido-fatty acids_, _amines_, _diamines_, and

_ptomaines_.

* * * * *

§ 19. I have preferred an arrangement which, as far as possible, follows

the order in which a chemical expert would search for an unknown

poison--hence an arrangement partly chemical and partly symptomatic.

First the chief gases which figure in the mortality statistics are

treated, and then follow in order other poisons.

A chemist, given a liquid to examine, would naturally test first its

reaction, and, if strongly alkaline or strongly acid, would at once

direct his attention to the mineral acids or to the alkalies. In other

cases, he would proceed to separate volatile matters from those that

were fixed, lest substances such as prussic acid, chloroform, alcohol,

and phosphorus be dissipated or destroyed by his subsequent operations.

Distillation over, the alkaloids, glucosides, and their allies would

next be naturally sought, since they can be extracted by alcoholic and

ethereal solvents in such a manner as in no way to interfere with an

_after_-search for metals.

The metals are last in the list, because by suitable treatment, after

all organic substances are destroyed, either by actual fire or powerful

chemical agencies, even the volatile metals may be recovered. The metals

are arranged very nearly in the same order as that in which they would

be separated from a solution--viz., according to their behaviour to

hydric and ammoniac sulphides.

There are a few poisons, of course, such as the oxalates of the

alkalies, which might be overlooked, unless sought for specially; but it

is hoped that this is no valid objection to the arrangement suggested,

which, in greater detail, is as follows:--

A.--POISONOUS GASES.

1. Carbon monoxide.

2. Chlorine.

3. Hydric sulphide.

B.--ACIDS AND ALKALIES.

1. Sulphuric acid.

2. Hydrochloric acid.

3. Nitric acid.

4. Potash.

5. Soda.

6. Ammonia.

7. Neutral sodium, potassium, and ammonium salts.

In nearly all cases of death from any of the above, the analyst, from

the symptoms observed during life, from the surrounding circumstances,

and from the pathological appearances and evident chemical reactions of

the fluids submitted, is put at once on the right track, and has no

difficulty in obtaining decided results.

C.--POISONOUS SUBSTANCES CAPABLE OF BEING SEPARATED BY DISTILLATION FROM

EITHER NEUTRAL OR ACID LIQUIDS.

1. Hydrocarbons.

2. Camphor.

3. Alcohols.

4. Amyl-nitrite.

5. Chloroform and other anæsthetics.

6. Carbon disulphide.

7. Carbolic acid.

8. Nitro-benzene.

9. Prussic acid.

10. Phosphorus.

The volatile alkaloids, which may also be readily distilled by strongly

alkalising the fluid, because they admit of a rather different mode of

treatment, are not included in this class.

D.--ALKALOIDS AND POISONOUS VEGETABLE PRINCIPLES SEPARATED FOR THE MOST

PART BY ALCOHOLIC SOLVENTS.

DIVISION I.--VEGETABLE ALKALOIDS.

1. Liquid volatile alkaloids, alkaloids of hemlock, nicotine,

piturie, sparteine, aniline.

2. The opium group of alkaloids.

3. The strychnine or tetanic group of alkaloids--strychnine, brucine,

igasurine.

4. The aconite group of alkaloids.

5. The mydriatic group of alkaloids--atropine, hyoscyamine, solanin,

cytisine.

6. The alkaloids of the veratrines.

7. Physostigmine.

8. Pilocarpine.

9. Taxine.

10. Curarine.

11. Colchicin.

12. Muscarine and the active principles of certain fungi.

There would, perhaps, have been an advantage in arranging several of the

individual members somewhat differently--_e.g._, a group might be made

of poisons which, like pilocarpine and muscarine, are antagonistic to

atropine; and another group suggests itself, the physiological action of

which is the opposite of the strychnos class; solanin (although classed

as a mydriatic, and put near to atropine) has much of the nature of a

glucoside, and the same may be said of colchicin; so that, if the

classification were made solely on chemical grounds, solanin would have

followed colchicin, and thus have marked the transition from the

alkaloids to the glucosides.

DIVISION II.--GLUCOSIDES.

1. The digitalis group.

2. Other poisonous glucosides acting on the heart.

3. Saponin.

The glucosides, when fairly pure, are easily recognised; they are

destitute of nitrogen, neutral in reaction, and split up into sugar and

other compounds when submitted to the action of saponifying agents, such

as boiling with dilute mineral acids.

DIVISION III.--CERTAIN POISONOUS ANHYDRIDES OF THE ORGANIC ACIDS.

1. Santonin.

2. Mezereon.

It is probable that this class will in a few years be extended, for

several other organic anitrogenous poisons exist, which, when better

known, will most likely prove to be anhydrides.

DIVISION IV.--VARIOUS VEGETABLE POISONOUS PRINCIPLES NOT ADMITTING OF

CLASSIFICATION UNDER THE PREVIOUS THREE DIVISIONS.

Ergot, picrotoxin, the poison of _Illicium religiosum_, cicutoxin,

_Æthusa cynapium_, _Œnanthe crocata_, croton oil, savin oil, the

toxalbumins of castor oil and _Abrus_.

The above division groups together various miscellaneous toxic

principles, none of which can at present be satisfactorily classified.

E.--POISONS DERIVED FROM LIVING OR DEAD ANIMAL SUBSTANCES.

DIVISION I.--POISONS SECRETED BY THE LIVING.

1. Poisonous amphibia.

2. Poison of the scorpion.

3. Poisonous fish.

4. Poisonous insects--spiders, wasps, bees, beetles, &c.

5. Snake poison.

DIVISION II.--POISONS FORMED IN DEAD ANIMAL MATTERS.

1. Ptomaines.

2. Poisoning by putrid or changed foods--sausage poisoning.

F.--THE OXALIC ACID GROUP.

G.--INORGANIC POISONS.

DIVISION I.--PRECIPITATED FROM A HYDROCHLORIC ACID SOLUTION BY HYDRIC

SULPHIDE--PRECIPITATE, YELLOW OR ORANGE.

Arsenic, antimony, cadmium.

DIVISION II.--PRECIPITATED BY HYDRIC SULPHIDE IN HYDROCHLORIC ACID

SOLUTION--BLACK.

Lead, copper, bismuth, silver, mercury.

DIVISION III.--PRECIPITATED FROM A NEUTRAL SOLUTION BY HYDRIC SULPHIDE.

Zinc, nickel, cobalt.

DIVISION IV.--PRECIPITATED BY AMMONIA SULPHIDE.

Iron, chromium, thallium, aluminium.

DIVISION V.--ALKALINE EARTHS.

Barium.

III.--Statistics.

§ 20. The number of deaths from poison (whether accidental, suicidal, or

homicidal), as compared with other forms of violent, as well as natural

deaths, possesses no small interest; and this is more especially true

when the statistics are studied in a comparative manner, and town be

compared with town, country with country.

The greater the development of commercial industries (especially those

necessitating the use or manufacture of powerful chemical agencies), the

more likely are accidents from poisons to occur. It may also be stated,

further, that the higher the mental development of a nation, the more

likely are its homicides to be caused by subtle poison--its suicides by

the euthanasia of chloral, morphine, or hemlock.

Other influences causing local diversity in the kind and frequency of

poisoning, are those of race, of religion, of age and sex, and the

mental stress concomitant with sudden political and social changes.

In the ten years from 1883-1892, there appear to have died from poison,

in England and Wales, 6616 persons, as shown in the following tables:--

DEATHS FROM POISON IN ENGLAND AND WALES DURING THE TEN YEARS 1883-92.

+----------------------------+---------+---------+---------+---------+

| | or | | | |

+----------------------------+----+----+----+----+----+----+----+----+

| | M. | F. | M. | F. | M. | F. | M. | F. |

| | | | | | | | | |

| | | | | | | | | |

|Arsenic, | 37| 14| 37| 20| 1| 1| 75| 35|

|Antimony, | 3| ...| 1| 2| ...| ...| 4| 2|

|Copper, | 4| 1| 2| 1| ...| ...| 6| 2|

|Lead, | 831| 209| 1| 2| ...| ...| 832| 211|

|Silver Nitrate, | 1| ...| ...| ...| ...| ...| 1| ...|

|Zinc Chloride (or Sulphate),| 7| ...| 4| ...| ...| ...| 11| ...|

|Mercury, | 22| 11| 16| 8| 2| 1| 40| 20|

|Chromic Acid, | 1| ...| ...| ...| ...| ...| 1| ...|

|Iron Perchloride, | ...| ...| ...| 1| ...| ...| ...| 1|

| | | | | | | | | |

| | | | | | | | | |

|Lime, | 2| ...| ...| 1| ...| ...| 2| 1|

|Barium Chloride, | 1| ...| ...| ...| ...| ...| 1| ...|

| | | | | | | | | |

| | | | | | | | | |

|Ammonia, | 39| 25| 18| 16| ...| ...| 57| 41|

|Caustic Soda, | 3| 4| ...| 1| ...| ...| 3| 5|

| „ Potash, | 8| 10| 1| ...| ...| ...| 9| 10|

|Potassic Chlorate, | 1| ...| ...| ...| ...| ...| 1| ...|

| „ Bichromate, | 2| 2| 7| 3| ...| ...| 9| 5|

| „ Bromide, | 1| ...| ...| ...| ...| ...| 1| ...|

| (Sorrel), | 1| 3| 1| 4| ...| ...| 2| 7|

| | | | | | | | | |

| | | | | | | | | |

|Sulphuric Acid, | 30| 9| 29| 24| 1| ...| 60| 33|

|Nitric „ | 18| 7| 18| 9| ...| ...| 36| 16|

|Hydrochloric Acid, | 48| 18| 83| 55| ...| ...| 131| 73|

|Oxalic „ | 17| 6| 114| 86| ...| ...| 131| 92|

|Tartaric „ | ...| 1| ...| ...| ...| ...| ...| 1|

|Acetic „ | 4| 3| ...| 2| ...| ...| 4| 5|

|Carbolic „ | 169| 101| 219| 271| ...| 1| 388| 373|

|Hydrofluoric „ | ...| ...| ...| 1| ...| ...| ...| 1|

|Lucifer matches), | 24| 47| 28| 56| ...| ...| 52| 103|

|Iodine, | 6| 7| 1| 1| ...| ...| 7| 8|

| | | | | | | | | |

| | | | | | | | | |

|Paraffin (Petroleum), | 9| 2| 1| ...| ...| ...| 10| 2|

|Benzoline, | 3| 2| ...| 1| ...| ...| 3| 3|

|Naphtha, | 1| ...| ...| ...| ...| ...| 1| ...|

|Carbon Bisulphide, | ...| ...| 1| ...| ...| ...| 1| ...|

|Turpentine, | 5| 1| ...| 3| ...| ...| 5| 4|

|Methylated Spirit, | ...| 2| 1| 2| ...| ...| 1| 4|

|Alcohol, | 81| 24| 1| 2| ...| ...| 82| 26|

|Chloroform, | 57| 41| 9| 5| 1| ...| 67| 46|

|Ether, | 5| 2| ...| ...| ...| ...| 5| 2|

|Spt. Etheris Nitrosi, | 1| ...| ...| ...| ...| ...| 1| ...|

|stated), | 4| 3| ...| ...| ...| ...| 4| 3|

|Oil of Juniper, | 1| ...| ...| ...| ...| ...| 1| ...|

| | | | | | | | | |

| | | | | | | | | |

|Opium, Laudanum--Morphia, | 503| 373| 330| 167| 4 | 2 | 837| 542|

|&c. | 18| 22| 2| 3| ...| ...| 20| 25|

|Chlorodyne, | 56| 30| 8| 8| ...| ...| 64| 38|

|Chloral, | 89| 22| 14| 1| 1 | ...| 104| 23|

| | | | | | | | | |

| | | | | | | | | |

| Almonds, | 17| 11| 203| 19| 2 | 8 | 222| 38|

|Potassium Cyanide, | 19| 21| 100| 22| 3 | 1 | 122| 44|

| | | | | | | | | |

| | | | | | | | | |

|Strychnine and Nux Vomica, | 22| 21| 65| 85| 4 | 4 | 91| 110|

|Vermin-Killer, | 2| 6| 49| 69| 1 | ...| 52| 75|

|Atropine, | 2| ...| 1| ...| ...| ...| 3| ...|

|Belladonna, | 36| 20| 11| 9| ...| ...| 47| 29|

|Aconite, | 19| 21| 9| 10| ...| ...| 28| 31|

|Ipecacuanha, | 1| 1| ...| ...| ...| ...| 1| 1|

|Cocaine, | 3| ...| ...| ...| ...| ...| 3| ...|

| | | | | | | | | |

| | | | | | | | | |

|Antipyrine, | 1| ...| ...| ...| ...| ...| 1| ...|

|Cantharides, | 1| ...| ...| 1| ...| ...| 1| 1|

|Camphorated Oil, | 1| ...| ...| ...| ...| ...| 1| ...|

|Croton Oil, | 1| ...| ...| ...| ...| ...| 1| ...|

|Cayenne Pepper, | 1| ...| ...| ...| ...| ...| 1| ...|

|Syrup of Rhubarb, | 1| ...| ...| ...| ...| ...| 1| ...|

|Colchicum, | 2| ...| ...| ...| ...| ...| 2| ...|

|Hemlock, | 3| 1| ...| ...| ...| ...| 3| 1|

|Water Hemlock, | 5| 6| ...| ...| ...| ...| 5| 6|

|Colocynth, | ...| 2| ...| ...| ...| ...| ...| 2|

|Castor Oil Seeds, | 1| 1| ...| ...| ...| ...| 1| 1|

|Laburnum Seeds, | 2| 1| ...| ...| ...| ...| 2| 1|

|Thorn Apple, | 1| ...| ...| ...| ...| ...| 1| ...|

|Yew Leaves or Berries, | 3| 2| ...| ...| ...| ...| 3| 2|

|Crow-foot, | ...| 1| ...| ...| ...| ...| ...| 1|

|Whin-flower, | 1| ...| ...| ...| ...| ...| 1| ...|

|Pennyroyal, | ...| 1| ...| ...| ...| ...| ...| 1|

|Meadow Crow-foot, | ...| 1| ...| ...| ...| ...| ...| 1|

|Arum Seeds, | ...| 1| ...| ...| ...| ...| ...| 1|

|Bitter Aloes, | ...| 1| ...| 1| ...| ...| ...| 2|

|Cocculus Indicus, | ...| ...| 1| ...| ...| ...| 1| ...|

|Horse Chestnut, | ...| 1| ...| ...| ...| ...| ...| 1|

|Creosote, | 1| ...| ...| ...| ...| ...| 1| ...|

|Spirits of Tar (Oil of Tar),| 2| 1| ...| ...| ...| ...| 2| 1|

|Nitro-Glycerine, | 1| ...| ...| ...| ...| ...| 1| ...|

|Camphor, | ...| 1| ...| ...| ...| ...| ...| 1|

|Tobacco, | 4| ...| 1| ...| ...| ...| 5| ...|

|Lobelia, | 1| ...| ...| ...| ...| ...| 1| ...|

|Fungi, | 13| 10| ...| ...| ...| ...| 13| 10|

|Poisonous Weeds, | 2| ...| ...| ...| ...| ...| 2| ...|

|Hellebores, | ...| ...| 1| 1| ...| ...| 1| 1|

|Kind not stated, | 216| 158| 256| 167| 3 | 1 | 475| 326|

| +----+----+----+----+----+----+----+----+

| |2498|1292|1644|1140| 23| 19|4165|2551|

| | \ / | \ / | \ / | \ / |

| | 3790 | 2784 | 42 | 6616 |

+----------------------------+---------+---------+---------+---------+

Although so large a number of substances destroy life by accident or

design, yet there are in the list only about 21 which kill about 2

persons or above each year: the 21 substances arranged in the order of

their fatality are as follows:--

Actual deaths in

ten years ending 1892.

Caustic potash 19

Poisonous fungi 23

Aconite 59

Mercury 60

Belladonna 76

Sulphuric acid 93

Ammonia 98

Chlorodyne 102

Alcohol 108

Arsenic 110

Chloroform 113

Vermin-killer 127

Chloral 127

Phosphorus 155

Cyanide of potassium 166

Strychnine 201

Nitric acid 204

Prussic acid 260

Carbolic acid 762

Lead 1043

Opiates 1324

In each decade there are changes in the position on the list. The most

significant difference between the statistics now given and the

statistics for the ten years ending 1880, published in the last edition

of this work, is that in the former decade carbolic acid occupied a

comparatively insignificant place; whereas in the ten years ending 1892,

deaths from carbolic acid poisoning are the most frequent form of fatal

poisoning save lead and opiates.

The following table gives some German statistics of poisoning:--

TABLE SHOWING THE ADMISSIONS INTO VARIOUS MEDICAL INSTITUTIONS[30] IN

BERLIN OF PERSONS SUFFERING FROM THE EFFECTS OF POISON DURING THE THREE

YEARS 1876, 1877, 1878.

[30] Viz., the Königl. Charité, Allg. Städtisches Krankenhaus,

Städtisches Baracken-Lazareth, Bethanien, St. Helwög’s-Lazarus,

Elisabethen-Krankenhaus, Augusta Hospital, and the Institut für

Staatsarzneikunde.

+--------------------------------------+--------+--------+--------+

+--------------------------------------+--------+--------+--------+

| Charcoal Vapour, | 77 | 78 | 155 |

| Sulphuric Acid, | 24 | 54 }| |

| Hydrochloric Acid, | 4 | 4 }| 93 |

| Nitric Acid, and Aqua Regia, | 7 | ... }| |

| Phosphorus, | 13 | 28 | 41 |

| Cyanide of Potassium, | 29 | 3 }| |

| Prussic Acid, | 5 | 1 }| 38 |

| Oxalic Acid, and Oxalate of Potash, | 11 | 8 | 19 |

| Alcohol, | 12 | 2 | 14 |

| Arsenic, | 7 | 5 | 12 |

| Morphine, | 8 | 1 }| |

| Opium, | 2 | 1 }| 12 |

| Potash or Soda Lye, | 2 | 6 | 8 |

| Chloral, | 3 | 4 | 7 |

| Chloroform, | 4 | 2 | 6 |

| Sewer Gas, | 5 | ... | 5 |

| Strychnine, | ... | 4 | 4 |

| Atropine, | 1 | 2 | 3 |

| Copper Sulphate, | 1 | 2 | 3 |

| Nitrobenzol, | 2 | ... | 2 |

| Carbolic Acid, | ... | 2 | 2 |

| Chromic Acid, | 1 | 1 | 2 |

| Burnt Alum, | ... | 1 | 1 |

| Ammonium Sulphide, | 1 | ... | 1 |

| Datura Stramonium, | ... | 1 | 1 |

| Petroleum, | ... | 1 | 1 |

| Benzine, | 1 | ... | 1 |

| Ether, | 1 | ... | 1 |

| Prussic Acid and Morphine, | 1 | ... | 1 |

| Prussic Acid and Chloral, | 1 | ... | 1 |

| Turpentine and Sal Ammoniac, | ... | 1 | 1 |

| +--------+--------+--------+

| | 223 | 212 | 435 |

+--------------------------------------+--------+--------+--------+

=Suicidal Poisoning.=--Poisons which kill more than one person

suicidally each year are only 19 in number, as follows:--

Deaths from suicide

during the ten years

ending 1892.

Potassic bichromate 10

Chloroform 14

Chloral 15

Chlorodyne 16

Aconite 19

Belladonna 20

Mercury 24

Nitric acid 27

Ammonia 34

Sulphuric acid 53

Arsenic 77

Phosphorus 84

Vermin-killer 118

Prussic acid 122

Hydrochloric acid 138

Strychnine 150

Oxalic acid 200

Prussic acid 222

Opiates 281

Phenol 290

In the ten years ending 1880, suicidal deaths from vermin-killers, from

prussic acid, from cyanide of potassium, and from opiates were all more

numerous than deaths from phenol, whereas at present phenol appears to

be the poison most likely to be chosen by a suicidal person.

Criminal Poisoning.

§ 22. Some useful statistics of criminal poisoning have been given by

Tardieu[31] for the 21 years 1851-1871, which may be summarised as

follows:--

[31] _Étude Médico-Légale sur l’Empoisonnement_, Paris, 1875.

Total accusations of Poisoning in the 21 years, 793

RESULTS OF THE POISONING:--

Death, 280 }

Illness, 346 } 872

Negative, 246 }

ACCUSED:--

Men, 304 } 703

Women, 399 }

NATURE OF POISON EMPLOYED:--

Arsenic, 287

Phosphorus, 267

{ Sulphate, 120 }

Copper { Acetate (Verdigris), 39 } 159

{ Sulphuric Acid, 36 }

Acids { Hydrochloric Acid, 8 } 47

{ Nitric Acid, 3 }

Cantharides, 30

Nux Vomica, 5 } 12

Strychnine, 7 }

{ Opium, 6 }

Opiates { Laudanum, 3 } 10

{ Sedative Water, 1 }

Salts of Mercury, 8

Sulphate of Iron, 6

Preparations of Antimony, 5

Ammonia, 4

Cyanides {Prussic Acid, 2 }

{Cyanide of Potassium, 2 } 4

Hellebore, 3

Datura Stramonium, 3

Powdered Glass, 3

Digitalin, 2

Potash, 2

Sulphate of Zinc, 2

Eau de Javelle (a solution of Hypochlorite of Potash), 1

Tincture of Iodine, 1

Croton Oil, 1

Nicotine, 1

Belladonna, 1

“Baume Fiovarenti,” 1

Euphorbia, 1

Acetate of Lead, 1

Carbonic Acid Gas, 1

Laburnum Seeds, 1

Colchicum, 1

Mushrooms, 1

Sulphuric Ether, 1

---

Total, 867

===

It hence may be concluded, according to these statistics of criminal

poisoning, that of 1000 attempts in France, either to injure or to

destroy human life by poison, the following is the most probable

selective order:--

Arsenic, 331

Phosphorus, 301

Preparations of Copper, 183

The Mineral Acids, 54

Cantharides, 35

Strychnine, 14

Opiates, 12

Mercurial preparations, 9

Antimonial preparations, 6

Cyanides (that is, Prussic Acid and Potassic Cyanide), 5

Preparations of Iron, 5

This list accounts for 955 poisonings, and the remaining 45 will be

distributed among the less used drugs and chemicals.

IV.--The Connection between Toxic Action and Chemical Composition.

§ 23. Considerable advance has been made of late years in the study of

the connection which exists between the chemical structure of the

molecule of organic substances and physiological effect. The results

obtained, though important, are as yet too fragmentary to justify any

great generalisation; the problem is a complicated one, and as Lauder

Brunton justly observes:--

“The physiological action of a drug does not depend entirely on its

chemical composition nor yet on its chemical structure, so far as that

can be indicated even by graphic formula, but upon conditions of

solubility, instability, and molecular relations, which we may hope to

discover in the future, but with which we are as yet imperfectly

acquainted.”[32]

[32] _Introduction to Modern Therapeutics_, Lond., 1892. 136.

The occurrence of hydroxyl, whether the substance belong to the simpler

chain carbon series or to the aromatic carbon compounds, appears to

usually endow the substance with more or less active and frequently

poisonous properties, as, for example, in the alcohols, and as in

hydroxylamine. It is also found that among the aromatic bodies the toxic

action is likely to increase with the number of hydroxyls: thus phenol

has one hydroxyl, resorcin two, and phloroglucin three; and the toxic

power is strictly in the same order, for, of the three, phenol is least

and phloroglucin most poisonous.

Replacing hydrogen by a halogen, especially by chlorine, in the fatty

acids mostly produces substances of narcotic properties, as, for

instance, monochloracetic acid. In the sulphur compounds, the entrance

of chlorine modifies the physiological action and intensifies toxicity:

thus ethyl sulphide (C₂H₅)₂S is a weak poison, monochlorethyl sulphide

C₂H₅C₂H₄ClS a strong poison, and dichlorethyl sulphide C₄H₈Cl₂S a very

strong poison: the vapour kills rabbits within a short time, and a trace

of the oil applied to the ear produces intense inflammation of both the

eyes and the ear.[33]

[33] V. Meyer, _Ber. d. Chem. Ges._, XX., 1725.

The weight of the molecule has an influence in the alcohols and acids of

the fatty series; for instance, ethyl, propyl, butyl, and amyl alcohols

show as they increase in carbon a regular increase in toxic power; the

narcotic actions of sodium propionate, butyrate, and valerianate also

increase with the rising carbon. Nitrogen in the triad condition in the

amines is far less poisonous than in the pentad condition.

Bamberger[34] distinguishes two classes of hydrogenised bases derived

from α and β naphthylamine, by the terms “acylic” and “aromatic.” The

acylic contains the four added hydrogens in the amidogen nucleus, the

aromatic in the other nucleus, thus

[34] _Ber._, xxii. 777-778.

CH CNH₂

/\ /\

/ \C/ \

CH | | | CH

| | |

CH | | | CH

\ /C\ /

\/ \/

CH CH

α Naphthylamine.

CH CH

/\ /\

/ \C/ \

CH | | | CNH₂

| | |

CH | | | CH

\ /C\ /

\/ \/

CH CH

β Naphthylamine.

CH CH₂

/\ /\

/ \C/ \

CH | | | CNH₃

| | |

CH | | | CH₂

\ /C\ /

\/ \/

CH CH₂

Acylic tetrahydro-α Naphthylamine.

CH₂ CH

/\ /\

/ \C/ \

CH₂ | | | CNH₂

| | |

CH₂ | | | CH

\ /C\ /

\/ \/

CH₂ CH

Aromatic tetrahydro-β Naphthylamine.

The acylic β tetrahydro-naphthylamine, the β

tetrahydroethylnaphthylamine, and the β tetrahydromethylnaphthylamine

all cause dilatation of the pupil and produce symptoms of excitation of

the cervical sympathetic nerve; the other members of the group are

inactive.

§ 24. The result of replacing hydrogen by alkyls in aromatic bodies has

been studied by Schmiedeberg and others; replacing the hydrogen of the

amidogen by ethyl or methyl, usually results in a body having a more or

less pronounced narcotic action. The rule is that methyl is stronger

than ethyl, but it does not always hold good; ortho-amido-phenol is not

in itself poisonous, but when two hydrogens of the amidogen group are

replaced by two methyls thus--

/ \

| |NH₂

| |

\ /

/ \

| |N(CH₃)₂

| |

\ /

the resulting body has a weak narcotic action.

It would naturally be inferred that the replacement of the H in the

hydroxyl by a third methyl would increase this narcotic action, but this

is not so: on the other hand, if there are three ethyl groups in the

same situation a decidedly narcotic body is produced.

The influence of position of an alkyl in the aromatic bodies is well

shown in ortho-, para- and meta-derivatives. Thus the author proved some

years ago that with regard to disinfecting properties, ortho-cresol was

more powerful than meta-; meta-cresol more powerful than para-; so again

ortho-aceto-toluid is poisonous, causing acute nephritis;

meta-aceto-toluid has but feeble toxic actions but is useful as an

antipyretic; and para-aceto-toluid is inactive.

In the trioxybenzenes, in which there are three hydroxyls, the toxic

action is greater when the hydroxyls are consecutive, as in pyrogallol,

than when they are symmetrical, as in phloroglucin.

/ \

| |OH

| |

| |OH

\ /

Pyrogallol.

/ \

| |

HO| |OH

\ /

Phloroglucin.

The introduction of methyl into the complicated molecule of an alkaloid

often gives curious results: thus methyl strychnine and methyl brucine

instead of producing tetanus have an action on voluntary muscle like

curare.

Benzoyl-ecgonine has no local anæsthetic action, but the introduction of

methyl into the molecule endows it with a power of deadening the

sensation of the skin locally; on the other hand, cocethyl produces no

effect of this kind.

Drs. Crum Brown and Fraser[35] have suggested that there is some

relation between toxicity and the saturated or non-saturated condition

of the molecule.

[35] _Journ. Anat. and Phys._, vol. ii. 224.

Hinsberg and Treupel have studied the physiological effect of

substituting various alkyls for the hydrogen of the hydroxyl group in

para-acetamido-phenol.

Para-aceto-amido-phenol when given to dogs in doses of 0.5 grm. for

every kilogr. of body weight causes slight narcotic symptoms, with

slight paralysis; there is cyanosis and in the blood much methæmoglobin.

In men doses of half a gramme (7·7 grains) act as an antipyretic,

relieve neuralgia and have weak narcotic effects.

The following is the result of substituting certain alkyls for H in the

HO group.

(1) =Methyl.=--The narcotic action is strengthened and the antipyretic

action unaffected. The methæmoglobin in the blood is somewhat less.

(2) =Ethyl.=--Action very similar, but much less methæmoglobin is

produced.

(3) =Propyl.=--Antipyretic action a little weaker. Methæmoglobin in the

blood smaller than in para-acetamido-phenol, but more than when the

methyl or ethyl compound is administered.

(4) =Amyl.=--Antipyretic action decreased.

The smallest amount of toxicity is in the ethyl substitution; while the

maximum antipyretic and antineuralgic action belongs to the methyl

substitution.

Next substitution was tried in the Imid group. It was found that

substituting ethyl for H in the imid group annihilated the narcotic and

antipyretic properties. No methæmoglobin could be recognised in the

blood.

Lastly, simultaneous substitution of the H of the HO group by ethyl and

the substitution of an alkyl for the H in the NH group gave the

following results:--

=Methyl.=--In dogs the narcotic action was strengthened, the

methæmoglobin in the blood diminished. In men the narcotic action was

also more marked as well as the anti-neural action. The stomach and

kidneys were also stimulated.

=Ethyl.=--In dogs the narcotic action was much strengthened, while the

methæmoglobin was diminished. In men the antipyretic and anti-neural

actions were unaffected.

=Propyl.=--In dogs the narcotic action was feebler than with methyl or

ethyl, and in men there was diminished antipyretic action.

=Amyl.=--In dogs the narcotic action was much smaller.

From this latter series the conclusion is drawn that the maximum of

narcotic action is obtained by the introduction of methyl and the

maximum antipyretic action by the introduction of methyl or ethyl. The

ethyl substitution is, as before, the less toxic.[36]

[36] _Ueber die physiologische Wirkung des p-amido-phenol u. einiger

Derivate desselben._ O. Hinsberg u. G. Treupel, _Archiv f. Exp. Pathol.

u. Pharm._, B. 33, S. 216.

The effect of the entrance of an alkyl into the molecule of a substance

is not constant; sometimes the action of the poison is weakened,

sometimes strengthened. Thus, according to Stolnikow, dimethyl resorcin,

C₆H₄(OCH₃)₂, is more poisonous than resorcin C₆H₄(OH)₂. Anisol C₆H₅OCH₃,

according to Loew, is more poisonous to algæ, bacteria, and infusoria

than phenol C₆H₅OH. On the other hand, the replacement by methyl of an

atom of hydrogen in the aromatic oxyacids weakens their action; methyl

salicylic acid

O.CH₃

C₆H₄

COOH

is weaker than salicylic acid

C₆H₄ .

COOH

Arsen-methyl chloride, As(CH₃)Cl₂, is strongly poisonous, but the

introduction of a second methyl As(CH₃)₂Cl makes a comparatively weak

poison.

§ 25. In some cases the increase of CO groups weakens the action of a

poison; thus, in allantoin there are three carbonyl (CO) groups; this

substance does not produce excitation of the spinal cord, but it

heightens muscular irritability and causes, like xanthin, muscular

rigidity; alloxantin, with a similar structure but containing six

carbonyl groups, does not possess this action.

NH--CH--NH

| | |

CO | CO

| | |

NH--CO NH₂

Allantoin.

NH--CO CO--HN

| | | |

| | O | |

| |/ \| |

CO--C---C CO

| | | |

NH--CO CO--HN

Alloxantin.

§ 26. A theory of general application has been put forward and supported

with great ability by Oscar Loew[37] which explains the action of

poisons by presuming that living has a different composition to dead

albumin; the albumin of the chemist is a dead body of a definite

composition and has a stable character; living albumin, such as

circulates in the blood or forms the protoplasm of the tissues, is not

“stable” but “labile”; Loew says:--“If the old idea is accepted that

living albumin is chemically the same substance as that which is dead,

numerous toxic phenomena are inexplicable. It is impossible, for

instance, to explain how it is that diamide N₂H₄ and hydroxylamine NH₂OH

are toxic, even with great dilution, on all living animals; whilst

neither of those substances have the smallest action on dead plasma or

the ordinary dissolved passive albumin, there must therefore be present

in the albumin of the living plasma a grouping of atoms in a “_labile_”

condition (_Atomgruppirungen labiler Art_) which are capable of entering

into reactions; such, according to our present knowledge, can only be

the aldehyde and the ketone groups. The first mentioned groups are more

labile and react in far greater dilution than the latter groups.”

[37] _Ein natürliches System der Gift-Wirkungen_, München, 1893.

Loew considers that all substances which enter into combination with

aldehyde or ketone groups must be poisonous to life generally. For

instance, hydroxylamine, diamide and its derivatives, phenylhydrazine,

free ammonia, phenol, prussic acid, hydric sulphide, sulphur dioxide and

the acid sulphites all enter into combination with aldehyde.

So again the formation of imide groups in the aromatic ring increases

any poisonous properties the original substance possesses, because the

imide group easily enters into combination with aldehyde; thus

piperidine (CH₂)₅NH is more poisonous than pyridine (CH)₅N; coniine

NH(CH₂)₄CH-CH₂-CH₂CH₃, is more poisonous than collidine

N(CH)₄C-CH-(CH₃)₂; pyrrol (CH)₄NH than pyridine (CH)₅N; and amarin,[38]

C₆H₅-CH-NH

| \

| CH-C₆H₅,

| /

C₆H₅-C=N

than hydrobenzamide

C₆H₅-CH=N

CH-C₆H₅.

C₆H₅-CH=N

[38] Th. Weyl (_Lehrbuch der organischen Chemie_) states (p. 385) that

amarin is not poisonous, but Baccheti (_Jahr. d. Chemie_, 1855) has

shown that 250 mgrms. of the acetate will kill a dog, 80 mgrms. a

guinea-pig; and that it is poisonous to fishes, birds, and frogs:

hydrobenzamide in the same doses has no effect.

If the theory is true, then substances with “labile” amido groups, on

the one hand, must increase in toxic activity if a second amido group is

introduced; and, on the other, their toxic qualities must be diminished

if the amido group is changed into an imido group by the substitution of

an atom of hydrogen for an alkyl.

Observation has shown that both of these requirements are satisfied;

phenylenediamine is more poisonous than aniline; toluylenediamine more

poisonous than toluidine. Again, if an atom of hydrogen in the amido

(NH₂) group in aniline be replaced by an alkyl, _e.g._ methyl or ethyl,

the resulting substance does not produce muscular spasm; but if the same

alkyl is substituted for an atom of hydrogen in the benzene nucleus the

convulsive action remains unaffected.

If an acidyl, as for example the radical of acetic acid, enter into the

amido group, then the toxic action is notably weakened; thus,

acetanilide is weaker than aniline, and acetylphenylhydrazine is weaker

than phenylhydrazine. If the hydrogen of the imido group be replaced by

an alkyl or an acid radical, and therefore tertiary bound nitrogen

restored, the poisonous action is also weakened.

In xanthin there are three imido groups; the hydrogen of two of these

groups is replaced by methyl in theobromin; and in caffein the three

hydrogens of the three imido groups are replaced by three methyls,

thus:--

NH--CH

| ║

CO C--NH

| | \

| | CO

| | /

NH--C==N

Xanthin.

N.CH₃--CH

| ║

CO C--N.CH₃

| | \

| | CO

| | /

NH-----C==N

Theobromin.

N.CH₃--CH

| ║

CO C--N.CH₃

| | \

| | CO

| | /

N.CH₃--C==N

Caffein.

and experiment has shown that theobromin is weaker than xanthin, and

caffein still weaker than theobromin.

Loew[39] makes the following generalisations:--

[39] _Ein natürliches System der Gift-Wirkungen_, München, 1893.

1. Entrance of the carboxyl or sulpho groups weakens toxic action.

2. Entrance of a chlorine atom exalts the toxic character of the

catalytic poisons (Loew’s catalytic poisons are alcohols, ether,

chloroform, chloral, carbon tetrachloride, methylal, carbon disulphide

and volatile hydrocarbons).

3. Entrance of hydroxyl groups in the catalytic poisons of the fatty

series weakens toxic character; on the other hand, it exalts the

toxicity of the substituting poisons. (Examples of Loew’s class of

“substituting” poisons are hydroxylamine, phenylhydrazine, hydric

cyanide, hydric sulphide, aldehyde, and the phenols.)

4. A substance increases in poisonous character through every influence

which increases its power of reaction with aldehyde or amido groups. If,

for example, an amido or imido group in the poison molecule be made more

“labile,” or if thrice linked nitrogen is converted into nitrogen

connected by two bands, whether through addition of water or

transposition (_umlagerung_) or if a second amido group enters, the

poisonous quality is increased. Presence of a negative group may modify

the action.

5. Entrance of a nitro group strengthens the poisonous character. If a

carboxyl or a sulpho group is present in the molecule, or if, in passing

through the animal body, negative groups combine with the poison

molecule, or carboxyl groups are formed in the said molecule; in such

cases the poisonous character of the nitro group may not be apparent.

6. Substances with double carbon linkings are more poisonous than the

corresponding saturated substances. Thus neurine with the double linking

of the carbon of CH₂ is more poisonous than choline; vinylamine than

ethylamine.

CH==CH₂

(CH₃)₃N

Neurine.

CH₂--CH₂OH

(CH₃)₃N

Choline.

CH₂

║

CH.NH₂

Vinylamine.

CH₃

CH₂.NH₂

Ethylamine.

§ 27. M. Ch. Michet[40] has investigated the comparative toxicity of the

metals by experiments on fish, using species of _Serranus_,

_Crenolabrus_, and _Julius_. The chloride of the metal was dissolved in

water and diluted until just that strength was attained in which the

fish would live 48 hours; this, when expressed in grammes per litre, he

called “_the limit of toxicity_.”

[40] “_De la Toxicité comparée des différents Métaux._” _Note de M. Ch.

Michet. Compt. Rend._, t. xciii., 1881, p. 649.

The following is the main result of the inquiry, by which it will be

seen that there was found no relation between “the limit of toxicity”

and the atomic weight.

TABLE SHOWING THE RESULTS OF EXPERIMENTS ON FISH.

No. of Limit of

Experiments. Metal. Toxicity.

20. Mercury, ·00029

7. Copper, ·0033

20. Zinc, ·0084

10. Iron, ·014

7. Cadmium, ·017

6. Ammonium, ·064

7. Potassium, ·10

10. Nickel, ·126

9. Cobalt, ·126

11. Lithium, ·3

20. Manganese ·30

6. Barium, ·78

4. Magnesium, 1·5

20. Strontium, 2·2

5. Calcium, 2·4

6. Sodium, 24·17

V.--Life-Tests; or the Identification of Poison by Experiments on

Animals.

§ 28. A philosophical investigation of poisons demands a complete

methodical examination into their action on every life form, from the

lowest to the highest. Our knowledge is more definite with regard to the

action of poisons on man, dogs, cats, rabbits, and frogs than on any

other species. It may be convenient here to make a few general remarks

as to the action of poisons on infusoria, the cephalopoda, and insects.

=Infusoria.=--The infusoria are extremely sensitive to the poisonous

alkaloids and other chemical agents. Strong doses of the alkaloids cause

a contraction of the cell contents, and somewhat rapid disintegration of

the whole body; moderate doses at first quicken the movements, then the

body gets perceptibly larger, and finally, as in the first case, there

is disintegration of the animal substance.

Rossbach[41] gives the following intimations of the proportion of the

toxic principle necessary to cause death:--Strychnine 1 part dissolved

in 1500 of water; veratrine 1 in 8000; quinine 1 in 5000; atropine 1 in

1000; the mineral acids 1 in 400-600; salts 1 in 200-300.

[41] N. J. Rossbach, _Pharm. Zeitschr. für Russland_, xix. 628.

The extraordinary sensitiveness of the infusoria, and the small amount

of material used in such experiments, would be practically useful if

there were any decided difference in the symptoms produced by different

poisons. But no one could be at all certain of even the class to which

the poison belongs were he to watch, without a previous knowledge of

what had been added to the water, the motions of poisoned infusoria.

Hence the fact is more curious than useful.

=Cephalopoda.=--The action of a few poisons on the cephalopoda has been

investigated by M. E. Yung.[42] Curara placed on the skin had no effect,

but on the branchiæ led to general paralysis. If given in even fifteen

times a greater dose than necessary to kill a rabbit, it was not always

fatal. Strychnine, dissolved in sea-water, in the proportion of 1 to

30,000, causes most marked symptoms. The first sign is relaxation of the

chromataphore muscle and the closing of the chromataphores; the animal

pales, the respiratory movements become more powerful, and at the end of

a notable augmentation in their number, they fall rapidly from the

normal number of 25 to 5 a minute. Then tetanus commences after a time,

varying with the dose of the poison; the arm stiffens and extends in

fan-like form, the entire body is convulsed, the respiration is in

jerks, the animal empties his pouch, and at the end of a few minutes is

dead, in a state of great muscular rigidity. If at this moment it is

opened, the venous heart is found still beating. Nicotine and other

poisons were experimented with, and the cephalopoda were found to be

generally sensitive to the active alkaloids, and to exhibit more or less

marked symptoms.

[42] _Compt. Rend._, t. xci. p. 306.

=Insects.=--The author devoted considerable time, in the autumn of 1882,

to observations on the effect of certain alkaloids on the common

blow-fly, thinking it possible that the insect would exhibit a

sufficient series of symptoms of physiological phenomena to enable it to

be used by the toxicologist as a living reagent. If so, the cheapness

and ubiquity of the tiny life during a considerable portion of the year

would recommend it for the purpose. Provided two blow-flies are caught

and placed beneath glass shades--the one poisoned, the other not--it is

surprising what a variety of symptoms can, with a little practice, be

distinguished. Nevertheless, the absence of pupils, and the want of

respiratory and cardiac movements, are, in an experimental point of

view, defects for which no amount or variety of merely muscular symptoms

can compensate.

From the nature of the case, we can only distinguish in the poisoned fly

dulness or vivacity of movement, loss of power in walking on smooth

surfaces, irritation of the integument, disorderly movements of the

limbs, protrusion of the fleshy proboscis, and paralysis, whether of

legs or wings. My experiments were chiefly made by smearing the extracts

or neutral solutions of poisons on the head of the fly. In this way some

of it is invariably taken into the system, partly by direct absorption,

and partly by the insect’s efforts to free itself from the foreign

substance, in which it uses its legs and proboscis. For the symptoms

witnessed after the application of saponin, digitalin, and aconitine,

the reader is referred to the articles on those substances.

In poisoning by sausages, bad meat, curarine, and in obscure cases

generally, in the present state of science, experiments on living

animals are absolutely necessary. In this, and in this way only, in very

many instances, can the expert prove the presence of zymotic, or show

the absence of chemical poison.

The Vivisection Act, however, effectually precludes the use of

life-tests in England save in licensed institutions. Hence the “methods”

of applying life-tests described in former editions will be omitted.

§ 29. =Effect of poisons on the heart of Cold-blooded Animals.=--The

Vivisection Act does not, however, interfere with the use of certain

living tests, such, for instance, as the testing of the action of

poisons upon the recently extirpated hearts of cold-blooded animals.

[Illustration: Williams’ Apparatus.]

The heart of the frog, of the turtle, of the tortoise, and of the

shark will beat regularly for a long time after removal from the

body, if supplied with a regular stream of nutrient fluid. The

fluids used for this purpose are the blood of the herbivora diluted

with common salt solution, or a serum albumin solution, or a 2 per

cent. solution of gum arabic in which red blood corpuscles are

suspended. The simplest apparatus to use is that known as

“Williams’.” Williams’ apparatus consists of two glass bulbs (see

diagram), the one, P, containing nutrient fluid to which a known

quantity of the poison has been added; the other, N, containing the

same fluid but to which no poison has been added; these bulbs are

connected by caoutchouc tubing to a three-way tube, T, and each

piece of caoutchouc tubing has a pressure screw clip, V¹ and V; the

three-way tube is connected with a wider tube containing a valve

float, F, which gives free passage of fluid in one direction only,

that is, in the direction of the arrow; this last wide tube is

connected with a Y piece of tubing, which again is connected with

the aorta of the heart under examination, the other leg of the Y

tube is connected with another wide tube, X, having a float valve,

F²: the float containing a drop of mercury and permitting (like the

float valve F) passage in one direction only of fluid, it is obvious

that if the clip communicating with N is opened and the clip

communicating with P is closed, the normal fluid will circulate

alone through the heart; if, on the other hand, the P clip is open

and the N clip closed, the poisoned blood will alone feed the heart.

It is also clear that by raising or depressing the bulbs, the

circulating fluid can be delivered at any pressure, high or low.

Should a bubble of air get into the tubes, it can be got rid of by

removing the cork at S and bringing the fluid up to the level of the

top of the aperture. The observation is made by first ascertaining

the number and character of the beats when the normal fluid is

circulating, and then afterwards when the normal is replaced by the

poisoned fluid. A simpler but less accurate process is to pith two

frogs, excise their respective hearts, and place the hearts in

watch-glasses containing either serum or a solution of common salt

(strength 0·75 per cent.); to the one heart is now added a solution

of the poison under examination, and the difference in the behaviour

and character of the beats noted.

The phenomena to be specially looked for are the following:--

1. The heart at the height of the poisoning is arrested in diastole.

2. The heart at the height of the poisoning is arrested in systole.

=Arrest in diastole.=--The arrest may be preceded by the

contractions becoming weaker and weaker, or after the so-called

heart peristalsis; or it may be preceded by a condition in which the

auricle shows a different frequency to the ventricle.

The final diastole may be the diastole of paralysis or the diastole

of irritation.

The diastole of irritation is produced by a stimulus of the

inhibitory ganglia, and only occurs after poisoning by the muscarine

group of poisons. This condition may be recognised by the fact that

contraction may be excited by mechanical and electrical stimuli or

by the application of atropine solution; the latter paralyses the

inhibitory nervous centres, and therefore sets the mechanism going

again. The diastole of paralysis is the most frequent form of death.

It may readily be distinguished from the muscarine diastole; for, in

muscarine diastole, the heart is full of blood and larger than

normal; but in the paralytic form the heart is not fully extended,

besides which, although, if normal blood replace that which is

poisoned, the beats may be restored for a short time, the response

is incomplete, and the end is the same; besides which, atropine does

not restore the beats. The diastole of paralysis may depend on

paralysis of the so-called excito-motor ganglia (as with iodal), or

from paralysis of the muscular structure (as with copper).

§ 30. =The effect of poisons on the iris.=--Several poisons affect

the pupil, causing either contraction or dilatation. The most

suitable animal is the cat; the pupil of the cat readily showing

either state.

=Toxic myosis, or toxic contraction of the pupil.=--There are two

forms of toxic myosis, one of which is central in its origin. In

this form, should the poison be applied to the eye itself, no marked

contraction follows; the poison must be swallowed or injected

subcutaneously to produce an effect. The contraction remains until

death.

The contraction in such a case is considered to be due to a

paralysis of the dilatation centre; it is a “_myosis paralytica

centralis_;” the best example of this is the contraction of the

pupil caused by morphine.

In the second case the poison, whether applied direct to the eye or

entering the circulation by subcutaneous injection, contracts the

pupil; the contraction persists if the eye is extirpated, but in all

cases the contraction may be changed into dilatation by the use of

atropine. An example of this kind of myosis is the action of

muscarine. It is dependent on the stimulation of the ends of the

nerves which contract the pupil, especially the ends of the _nervus

oculomotorius_ supplying the sphincter iridis; this form of myosis

is called _myosis spastica periphera_. A variety of this form is the

_myosis spastica muscularis_, depending on stimulation of the musc.

sphincter iridis, seen in poisoning by physostigmine. This causes

strong contraction of the pupil when locally applied; the

contraction is not influenced by small local applications of

atropine, but it may be changed to dilatation by high doses.

Subcutaneous injection of small doses of physostigmine does not

alter the pupil, but large poisonous doses contracts the pupil in a

marked manner.

=Toxic mydriasis, or toxic dilatation of the pupil.=--The following

varieties are to be noticed:--

1. Toxic doses taken by the mouth or given by subcutaneous injection

give rise to strong dilatation; this vanishes before death, giving

place to moderate contraction. This form is due to stimulation of

the dilatation centre, later passing into paralysis. An example is

found in the action of aconite.

2. After subcutaneous or local application, a dilatation neutralised

by physostigmine in moderate doses. This is characteristic of

β-tetrahydronaphthylamine.

3. After subcutaneous injection, or if applied locally in very small

doses, dilatation occurs persisting to death. Large doses of

physostigmine neutralise the dilatation, but it is not influenced by

muscarine or pilocarpine: this form is characteristic of atropine,

and it has been called _mydriasis paralytica periphera_.

The heart at the height of the poisoning stops in systole.

=2. Arrest in systole.=--The systole preceding the arrest is far

stronger than normal, the ventricle often contracting up into a

little lump. Contraction of this kind is specially to be seen in

poisoning by digitalis. In poisoning by digitalis the ventricle is

arrested before the auricle; in muscarine poisoning the auricle

stops before the ventricle. If the reservoir of Williams’ apparatus

is raised so as to increase the pressure within the ventricle the

beat may be restored for a time, to again cease.

A frog’s heart under the influence of any poison may be finally

divided into pieces so as to ascertain if any parts still contract;

the significance of this is, that the particular ganglion supplying

that portion of the heart has not been affected: the chief ganglia

to be looked for are Remak’s, on the boundary of the sinus and

auricle; Ludwig’s, on the auricle and the septum of the auricle;

Bidder’s, on the atrioventricular border, especially in the valves;

and Dogiel’s ganglion, between the muscular fibres. According to

Dogiel, poisons acting like muscarine affect every portion of the

heart, and atropine restores the contractile power of every portion.

VI.--General Method of Procedure in Searching for Poison.

§ 31. Mineral substances, or liquids containing only inorganic matters,

can cause no possible difficulty to any one who is practised in

analytical investigation; but the substances which exercise the skill of

the expert are organic fluids or solids.

The first thing to be done is to note accurately the manner in which the

samples have been packed, whether the seals have been tampered with,

whether the vessels or wrappers themselves are likely to have

contaminated the articles sent; and then to make a very careful

observation of the appearance, smell, colour, and reaction of the

matters, not forgetting to take the weight, if solid--the volume, if

liquid. All these are obvious precautions, requiring no particular

directions.

If the object of research is the stomach and its contents, the contents

should be carefully transferred to a tall conical glass; the organ cut

open, spread out on a sheet of glass, and examined minutely by a lens,

picking out any suspicious-looking substance for closer observation.

The mucous membrane should now be well cleansed by the aid of a

wash-bottle, and if there is any necessity for destroying the stomach,

it may be essential in important cases to have it photographed. The

washings having been added to the contents of the stomach, the sediment

is separated and submitted to inspection, for it must be remembered

that, irrespective of the discovery of poison, a knowledge of the nature

of the food last eaten by the deceased may be of extreme value.

If the death has really taken place from disease, and not from poison,

or if it has been caused by poison, and yet no definite hint of the

particular poison can be obtained either by the symptoms or by the

attendant circumstances, the analyst has the difficult task of

endeavouring to initiate a process of analysis which will be likely to

discover any poison in the animal, vegetable, or mineral kingdom. For

this purpose I have devised the following process, which differs from

those that have hitherto been published mainly in the prominence given

to operations in a high vacuum, and the utilisation of biological

experiment as a matter of routine. Taking one of the most difficult

cases that can occur--viz., one in which a small quantity only of an

organic solid or fluid is available--the best method of procedure is the

following:--

[Illustration]

A small portion is reserved and examined microscopically, and, if

thought desirable, submitted to various “cultivation” experiments. The

greater portion is at once examined for volatile matters, and having

been placed in a strong flask, and, if neutral or alkaline, feebly

acidulated with tartaric acid, connected with a second or receiving

flask by glass tubing and caoutchouc corks. The caoutchouc cork of the

receiving flask has a double perforation, so as to be able, by a second

bit of angle tubing, to be connected with the mercury-pump described in

the author’s work on “Foods,” the figure of which is here repeated (see

the accompanying figure). With a good water-pump having a sufficient

length of fall-tube, a vacuum may be also obtained that for practical

purposes is as efficient as one caused by mercury; if the fall-tube

delivers outside the laboratory over a drain, no offensive odour is

experienced when dealing with putrid, stinking liquids. A vacuum having

been obtained, and the receiving-flask surrounded with ice, a distillate

for preliminary testing may be generally got without the action of any

external heat; but if this is too slow, the flask containing the

substances or liquid under examination may be gently heated by a

water-bath--water, volatile oils, a variety of volatile substances, such

as prussic acid, hydrochloric acid, phosphorus, &c., if present, will

distil over. It will be well to free in this way the substance, as much

as possible, from volatile matters and water. When no more will come

over, the distillate may be carefully examined by redistillation and the

various appropriate tests.

[Illustration: This figure is from “Foods.” B is a bell-jar, which can

be adapted by a cork to a condenser; R is made of iron; the rim of the

bell-jar is immersed in mercury, which the deep groove receives.]

The next step is to dry the sample thoroughly. This is best effected

also in a vacuum by the use of the same apparatus, only this time the

receiving-flask is to be half filled with strong sulphuric acid. By now

applying very gentle heat to the first flask, and cooling the sulphuric

acid receiver, even such substances as the liver in twenty-four hours

may be obtained dry enough to powder.

Having by these means obtained a nearly dry friable mass, it is reduced

to a coarse powder, and extracted with petroleum ether; the extraction

may be effected either in a special apparatus (as, for example, in a

large “Soxhlet”), or in a beaker placed in the “Ether recovery

apparatus” (see fig.), which is adapted to an upright condenser. The

petroleum extract is evaporated and leaves the fatty matter, possibly

contaminated by traces of any alkaloid which the substance may have

contained; for, although most alkaloids are insoluble in petroleum

ether, yet they are taken up in small quantities by oils and fats, and

are extracted with the fat by petroleum ether. It is hence necessary

always to examine the petroleum extract by shaking it up with water,

slightly acidulated with sulphuric acid, which will extract from the fat

any trace of alkaloid, and will permit the discovery of such alkaloids

by the ordinary “group reagents.”

The substance now being freed for the most part from water and from fat,

is digested in the cold with absolute alcohol for some hours; the

alcohol is filtered off, and allowed to evaporate spontaneously, or, if

speed is an object, it may be distilled _in vacuo_. The treatment is

next with hot alcohol of 90 per cent., and, after filtering, the dry

residue is exhausted with ether. The ether and alcohol, having been

driven off, leave extracts which may be dissolved in water and tested,

both chemically and biologically, for alkaloids, glucosides, and organic

acids. It must also be remembered that there are a few metallic

compounds (as, for example, corrosive sublimate) which are soluble in

alcohol and ethereal solvents, and must not be overlooked.

The residue, after being thus acted upon successively by petroleum, by

alcohol, and by ether, is both water-free and fat-free, and also devoid

of all organic poisonous bases and principles, and it only remains to

treat it for metals. For this purpose, it is placed in a retort, and

distilled once or twice to dryness with a known quantity of strong, pure

hydrochloric acid.

If arsenic, in the form of arsenious acid, were present, it would distil

over as a trichloride, and be detected in the distillate; by raising the

heat, the organic matter is carbonised, and most of it destroyed. The

distillate is saturated with hydric sulphide, and any precipitate

separated and examined. The residue in the retort will contain the fixed

metals, such as zinc, copper, lead, &c. It is treated with dilute

hydrochloric acid, filtered, the filtrate saturated with SH₂ and any

precipitate collected. The filtrate is now treated with sufficient sodic

acetate to replace the hydric chloride, again saturated with SH₂ and any

precipitate collected and tested for _zinc_, _nickel_, and _cobalt_. By

this treatment, viz.:--

1. Distillation in a vacuum at a low temperature,

2. Collecting the volatile products,

3. Dehydrating the organic substances,

4. Dissolving out from the dry mass fatty matters and alkaloids,

glucosides, &c., by ethereal and alcoholic solvents,

5. Destroying organic matter and searching for metals,

--a very fair and complete analysis may be made from a small amount of

material. The process is, however, somewhat faulty in reference to

phosphorus, and also to oxalic acid and the oxalates; these poisons, if

suspected, should be specially searched for in the manner to be more

particularly described in the sections treating of them. In most cases,

there is sufficient material to allow of division into three parts--one

for organic poisons generally, one for inorganic, and a third for

reserve in case of accident. When such is the case, although, for

organic principles, the process of vacuum distillation just described

still holds good, it will be very much the most convenient way not to

use that portion for metals, but to operate on the portion reserved for

the inorganic poisons as follows by destruction of the organic matter.

The destruction of organic matter through simple distillation by means

of pure hydrochloric acid is at least equal to that by sulphuric acid,

chlorate of potash, and the carbonisation methods. The object of the

chemist not being to dissolve every fragment of cellular tissue, muscle,

and tendon, but simply all mineral ingredients, the less organic matter

which goes into solution the better. That hydrochloric acid would fail

to dissolve sulphate of baryta and sulphate of lead, and that sulphide

of arsenic is also almost insoluble in the acid, is no objection to the

process recommended, for it is always open to the analyst to treat the

residue specially for these substances. The sulphides precipitated by

hydric sulphide from an acid solution are--arsenic, antimony, tin,

cadmium, lead, bismuth, mercury, copper, and silver. Those not

precipitated are--iron, manganese, zinc, nickel, and cobalt.

As a rule, one poison alone is present; so that if there should be a

sulphide, it will belong only exceptionally to more than one metal.

The colour of the precipitate from hydric sulphide is either yellowish

or black. The yellow and orange precipitates are sulphur, sulphides of

arsenic, antimony, tin, and cadmium. In pure solutions they may be

almost distinguished by their different hues, but in solutions

contaminated by a little organic matter the colours may not be

distinctive. The sulphide of arsenic is of a pale yellow colour; and if

the very improbable circumstance should happen that arsenic, antimony,

and cadmium occur in the same solution, the sulphide of arsenic may be

first separated by ammonia, and the sulphide of antimony by sulphide of

sodium, leaving cadmic sulphide insoluble in both processes.

The black precipitates are--lead, bismuth, mercury, copper, and silver.

The black sulphide is freed from arsenic, if present, by ammonia, and

digested with dilute nitric acid, which will dissolve all the sulphides,

save those of mercury and tin, so that if a complete solution is

obtained (sulphur flocks excepted), it is evident that both these

substances are absent. The presence of copper is betrayed by the blue

colour of the nitric acid solution, and through its special reactions;

lead, by the deep yellow precipitate which falls by the addition of

chromate of potash and acetate of soda to the solution; bismuth, through

a white precipitate on dilution with water. If the nitric acid leaves a

black insoluble residue, this is probably sulphide of mercury, and

should be treated with concentrated hydrochloric acid to separate flocks

of sulphur, evaporated to dryness, again dissolved, and tested for

mercury by iodide of potassium, copper foil, &c., as described in the

article on _Mercury_. Zinc, nickel, and cobalt are likewise tested for

in the filtrate as described in the respective articles on these metals.

AUTENRIETH’S GENERAL PROCESS.

§ 32. A general method of procedure has been published by W.

Autenrieth.[43]

[43] _Kurze Anleitung zur Auffindung der Gifte_, Freiburg, 1892.

He divides poisonous substances, for the purposes of separation and

detection, into three classes:--

I. Poisons capable of distillation from an acid aqueous solution.

II. Organic substances which are not capable of distillation from

acid solutions.

III. Metallic poisons.

Where possible, the fluid or solids submitted to the research are

divided into four equal parts, one of the parts to be kept in

reserve in case of accident or as a control; one of the remaining

three parts to be distilled; a second to be investigated for organic

substances; and a third for metals. After the extraction of organic

substances from part No. II. the residue may be added to No. III.

for the purpose of search after metals; and, if the total quantity

is small, the whole of the process may be conducted without

division.

I. SUBSTANCES SEPARATED BY DISTILLATION.

The substances are placed in a capacious flask, diluted if necessary

with water to the consistence of a thin soup, and tartaric acid

added to distinct acid reaction, and distilled.

In this way phosphorus, prussic acid, carbolic acid, chloroform,

chloral hydrate, nitrobenzol, aniline,[44] and alcohol may be

separated and identified by the reactions given in the sections of

this work describing those substances.

[44] Aniline is a weak base, so that, although a solution be acid, some

of the aniline distils over on heating.

II. ORGANIC POISONS NOT VOLATILE IN ACID SOLUTION.

Part No. II. is mixed with double its volume of absolute alcohol,

tartaric acid added to distinct acid reaction and placed in a flask

connected with an inverted Liebig’s condenser; it is then warmed for

15 to 20 minutes on the water-bath. After cooling, the mixture is

filtered, the residue well washed with alcohol and evaporated to a

thin syrup in a porcelain dish over the water-bath. The dish is then

allowed to cool and digested with 100 c.c. of water; fat and

resinous matters separate, the watery solution is filtered through

Swedish paper previously moistened: if the fluid filtrate is clear

it may be at once shaken up with ether, but if not clear, and

especially if it is more or less slimy, it is evaporated again on

the water-bath to the consistence of an extract: the extract treated

with 60 to 80 c.c. of absolute alcohol (which precipitates mucus and

dextrin-like substances), the alcohol evaporated off and the residue

taken up with from 60 to 80 c.c. of distilled water; it is then

shaken up with ether, as in Dragendorff’s process, and such

substances as digitalin, picric acid, salicylic acid, antipyrin and

others separated in this way and identified.

After this treatment with ether, and the separation of the ether

extract, the watery solution is strongly alkalised with caustic soda

and shaken up again with ether, which dissolves almost every

alkaloid save morphine and apomorphine; the ethereal extract is

separated and any alkaloid left identified by suitable tests.

The aqueous solution, now deprived of substances soluble in ether

both from acid and from solutions made alkaline by soda, is now

investigated for morphine and apomorphine; the apomorphine being

separated by first acidifying a portion of the alkaline solution

with hydrochloric acid, then alkalising with ammonia and shaking out

with ether. The morphine is separated from the same solution by

shaking out with warm chloroform.[45]

[45] Hot amyl alcohol would be better (see “Morphine”).

III. METALS.

The substances are placed in a porcelain dish and diluted with a

sufficient quantity of water to form a thin soup and 20 to 30 c.c.

of pure hydrochloric acid added; the dish is placed on the

water-bath and 2 grms. of potassic chlorate added. The contents are

stirred from time to time, and successive quantities of potassic

chlorate are again added, until the contents are coloured yellow.

The heating is continued, with, if necessary, the addition of more

acid, until all smell of chlorine has ceased. If there is

considerable excess of acid, this is to be evaporated away by

diluting with a little water and continuing to heat on the

water-bath. The dish with its contents is cooled, a little water

added, and the fluid is then filtered.

The metals remaining on the filter are:--

Silver chloride,

Lead sulphate,

Barium sulphate;

in the filtrate will be all the other metals.

The filtrate is put in a flask and heated to from 60 to 80 degrees

and submitted to a slow stream of hydric sulphide gas; when the

fluid is saturated with the gas, the flask is securely corked and

allowed to rest for twelve hours; at the end of that time the fluid

is filtered and the filter washed with water saturated with hydric

sulphide.

The still moist sulphides remaining on the filter are treated with

yellow ammonium sulphide containing some free ammonia and washed

with sulphide of ammonium water. Now remaining on the filter, if

present at all, will be:--

Mercury sulphide,

Lead sulphide,

Copper sulphide,

Cadmium sulphide;

in the filtrate may be:--

Arsenic sulphide,

Antimony sulphide,

Tin sulphide,

and there may also be a small portion of copper sulphide, because

the latter is somewhat soluble in a considerable quantity of

ammonium sulphide.

The filtrate from the original hydric sulphide precipitate will

contain, if present, the sulphides of zinc and chromium in solution.

INVESTIGATION OF THE SULPHIDES SOLUBLE IN AMMONIUM SULPHIDE, VIZ.,

ARSENIC, ANTIMONY, TIN.

The ammonium sulphide solution is evaporated to dryness in a

porcelain dish, strong nitric acid added and again dried. To this

residue a little strong caustic soda solution is added, and then it

is intimately mixed with three times its weight of a mixture

composed of 2 of potassic nitrate to 1 of dry sodium hydrate. This

is now cast, bit by bit, into a red-hot porcelain crucible. The

whole is heated until it has melted into a colourless fluid.

Presuming the original mass contained arsenic, antimony, and tin,

the melt contains sodic arseniate, sodic pyro-antimonate, sodic

stannate, and tin oxide; it may also contain a trace of copper

oxide.

The melt is cooled, dissolved in a little water, and sodium

bicarbonate added so as to change any caustic soda remaining into

carbonate, and to decompose the small amount of sodic stannate; the

liquid is then filtered.

The filtrate will contain the arsenic as sodic arseniate; while on

the filter there will be pyro-antimonate of soda, tin oxide, and,

possibly, a little copper oxide.

The recognition of these substances now is not difficult (see the

separate articles on _Antimony_, _Tin_, _Zinc_, _Arsenic_,

_Copper_).

INVESTIGATION OF THE SULPHIDES INSOLUBLE IN SULPHIDE OF AMMONIUM, VIZ.,

MERCURY, LEAD, COPPER, CADMIUM.

If the precipitate is contaminated with organic matter, it is

treated with hydrochloric acid and potassic chlorate in the manner

already described, p. 51.

Afterwards it is once more saturated with hydric sulphide, the

precipitate is collected on a filter, well washed, and the sulphides

treated with moderately concentrated nitric acid (1 vol. nitric

acid, 2 vols. water). The sulphides are best treated with this

solvent on the filter; all the sulphides mentioned, save mercury

sulphide, dissolve and pass into the filtrate. This mercury sulphide

may be dissolved by nitro-muriatic acid, the solution evaporated to

dryness, the residue dissolved in water acidified with hydrochloric

acid and tested for mercury (see “Mercury”).

The filtrate containing, it may be, nitrates of lead, copper and

cadmium is evaporated nearly to dryness and taken up in a very

little water. The lead is separated as sulphate by the addition of

dilute sulphuric acid.

The filtered solution, freed from lead, is treated with ammonia to

alkaline reaction; if copper be present, a blue colour is produced,

and this may be confirmed by other tests (see “Copper”). To detect

cadmium in the presence of copper, potassic cyanide is added to the

blue liquid until complete decolorisation, and the liquid treated

with SH₂; if cadmium be present, it is thrown down as a yellow

sulphide, while potassic cupro-cyanide remains in solution.

SEARCH FOR ZINC AND CHROMIUM.

The filtrate from the hydric sulphide precipitate is divided into

two parts; the one half is used in the search for zinc, the other

half is used for chromium.

=Search for Zinc.=--The liquid is alkalised with ammonia and then

ammonium sulphide is added. There will always be a precipitate of a

dark colour; the precipitate will contain earthy phosphates, iron

and, in some cases, manganese. The liquid with the precipitate is

treated with acetic acid to strong acid reaction and allowed to

stand for several hours. The portion of the precipitate remaining

undissolved is collected on a filter, washed, dried and heated to

redness in a porcelain crucible. The residue thus heated is cooled

and dissolved in a little dilute sulphuric acid. To the acid

solution ammonia is added, and any precipitate formed is treated

with acetic acid; should the precipitate not completely dissolve,

phosphate of iron is present; this is filtered off, and if SH₂ be

added to the filtrate, white zinc sulphide will come down (see

“Zinc”).

=Search for Chromium.=--The second part of the SH₂ filtrate is

evaporated to a thin extract, mixed with double its weight of sodic

nitrate, dried and cast, little by little, into a red-hot porcelain

crucible. When the whole is fully melted, the crucible is removed

from the flame, cooled, and the mass dissolved in water and

filtered. Any chromium present will now be in solution in the easily

recognised form of potassic chromate (see “Chromium”).

INVESTIGATION OF THE RESIDUE (p. 52) AFTER THE TREATMENT OF THE ORIGINAL

SUBSTANCE WITH HYDROCHLORIC ACID AND POTASSIC CHLORATE FOR PRESENCE OF

SILVER CHLORIDE, LEAD AND BARIUM SULPHATES.

The residue is dried and intimately mixed with three times its

weight of a mixture containing 2 parts of sodic nitrate and 1 part

of sodium hydrate, This is added, little by little, into a red-hot

porcelain crucible. The melted mass is cooled, dissolved in a little

water, a current of CO₂ passed through the solution to convert any

caustic soda into carbonate, and the solution boiled. The result

will be an insoluble portion consisting of carbonates of lead and

baryta, and of metallic silver. The mixture is filtered; the

insoluble residue on the filter is warmed for some time with dilute

nitric acid; the solution of nitrates of silver, lead and barium are

concentrated on the water-bath nearly to dryness so as to get rid of

any excess of acid, and the nitrates dissolved in water; then the

silver is precipitated by hydrochloric acid, the lead by SH₂, and

the barium by sulphuric acid.

VII.--The Spectroscope as an aid to the Identification of certain

Poisons.

§ 33. The spectra of many of the metals, of phosphine, of arsine and of

several other inorganic substances are characteristic and easily

obtained.

It is, however, from the employment of the _micro-spectroscope_ that the

toxicologist is likely to get most assistance.

[Illustration]

Oscar Brasch[46] has within the last few years studied spectroscopy in

relation to the alkaloids and organic poisons. Some of these, when mixed

with Froehde’s reagent, or with sulphuric acid, or with sulphuric acid

and potassic dichromate, or with nitric acid, give characteristic

colours, and the resulting solutions, when examined by a spectroscope,

for the most part show absorption bands; these bands may, occasionally,

assist materially in the identification of a poison. By far the best

apparatus is a micro-spectroscope of the Sorby and Browning type, to

which is added an apparatus for measuring the position on a scale of the

lines and bands. Seibert and Kraft of Wetzlar make an excellent

instrument, in which a small bright triangle is projected on the

spectrum; this can be moved by a screw, so that the apex may be brought

exactly in the centre of any line or band, and its position read on an

outside scale. The first thing to be done with such an instrument is to

determine the position on the scale of the chief Fraunhofer lines or of

the more characteristic lines of the alkalies and alkaline earths,[47]

the wave lengths of which are accurately known. If, now, the scale

divisions are set out as abscissæ, and the wave lengths in millionths of

a millimetre are made the ordinates of a diagram, and an equable curve

plotted out, as fully explained in the author’s work on “Foods,” it is

easy to convert the numbers on the scale into wave lengths, and so make

the readings applicable to any spectroscope. For the purpose of

graphical illustration the curve method is convenient, and is adopted in

the preceding diagrams, all taken from Oscar Brasch’s monograph. Where

the curve is highest there the absorption band is thickest; where the

curve is lowest there the band is weak. The fluid to be examined is

simply placed in a watch-glass, the watch-glass resting on the

microscope stand.

[46] _Ueber Verwendbarkeit der Spectroscopie zur Unterscheidung der

Farbenreactionen der Gifte im Interesse der forensischen Chemie_,

Dorpat, 1890.

[47] The alkalies and earths used for this purpose, with their wave

lengths, are as follows: KCl, a line in the red λ 770, in the violet λ

404. Lithium chloride, red line, 670·5; sodium chloride, yellow, 589;

strontium chloride, line in the blue, 461. It is also useful to measure

the green line of thallium chloride = 535.

[Illustration: CURVES INDICATING THE POSITION OF ABSORPTION BANDS ON

TREATING CERTAIN ALKALOIDS WITH REAGENTS.

NOTES TO CURVES INDICATING ABSORPTION BANDS.

1. Strychnine, treated with sulphuric acid and potassic dichromate

(violet).

2. Brucine, treated with potassic nitrate and sulphuric acid (clear

red).

3. Quebrachine, treated with vanadium sulphate (dark blue).

4. Quinine, Vogel’s reaction (red).

5. Caffein, Murexid reaction (violet-red).

6. Dephinoidin, Froehde’s reagent (cherry-red).

7. Veratrine, treated with sulphuric acid (straw-yellow).

8. „ „ „ (cherry-red).

9. „ „ „ (carmine-red).

10. Veratrine, Furfurol reaction (blue-violet).

11. Sabadillin, treated with sulphuric acid (red).

12. Veratroidine, „ „ (brown-red).

13. Jervine, Furfurol reaction (blue).

14. Sabadine, „ „ (blue).

15. Sabadine, treated with sulphuric acid (cherry-red).

16. Physostigmine, „ „ (grass-green).

17. Morphine, treated with Froehde’s reagent and sugar (dark-green).

18. Narcotine, treated with a mixture of sulphuric acid and nitric

acid (30 drops of sulphuric to 1 drop of nitric), (red).

19. Codeine, treated with Froehde’s reagent and sugar (dark violet).

20. Papaverine, treated with Froehde’s reagent (green-blue).

21. Sanguinarin, „ „ (violet-red).

22. Chelidonin, „ sulphate of vanadium (dark green).

23. Solanin, „ sulphuric acid and allowed to stand 4

hours (brown-red).

24. Digitalin, „ Erdmann’s reagent (red).

25. Aniline, „ sulphuric acid and potassic dichromate

(blue).]

The wave lengths corresponding to the numbers on the scale in the

diagram are as follows:--

W.L.

0 732

1 656

2 589·2

3 549·8

4 510·2

5 480·0

6 458

7 438

Examination of Blood, or of Blood-Stains.

§ 34. Spots, supposed to be blood--whether on linen, walls, or

weapons--should, in any important case, be photographed before any

chemical or microscopical examination is undertaken. Blood-spots,

according to the nature of the material to which they are adherent, have

certain naked eye peculiarities--_e.g._, blood on fabrics, if dry, has

at first a clear carmine-red colour, and part of it soaks into the

tissue. If, however, the tissue has been worn some time, or was

originally soiled, either from perspiration, grease, or filth, the

colour may not be obvious or very distinguishable from other stains;

nevertheless, the stains always impart a certain stiffness, as from

starch, to the tissue. If the blood has fallen on such substances as

wood or metal, the spot is black, has a bright glistening surface, and,

if observed by a lens, exhibits radiating fissures and a sort of

pattern, which, according to some, is peculiar to each species; so that

a skilled observer might identify occasionally, from the pattern alone,

the animal whence the blood was derived. The blood is dry and brittle,

and can often be detached, or a splinter of it, as it were, obtained.

The edges of the splinter, if submitted to transmitted light, are

observed to be red. Blood upon iron is frequently very intimately

adherent; this is specially the case if the stain is upon rusty iron,

for hæmatin forms a compound with iron oxide. Blood may also have to be

recovered from water in which soiled articles have been washed, or from

walls, or from the soil, &c. In such cases the spot is scraped off from

walls, plaster, or masonry, with as little of the foreign matters as may

be. It is also possible to obtain the colouring-matter of blood from its

solution in water, and present it for farther examination in a

concentrated form, by the use of certain precipitating agents (see p.

61).

In the following scheme for the examination of blood-stains, it is

presumed that only a few spots of blood, or, in any case, a small

quantity, is at the analyst’s disposal.

(1) The dried spot is submitted to the action of a cold saturated

solution of borax. This medium (recommended by Dragendorff)[48] does

certainly dissolve out of linen and cloth blood-colouring matter with

great facility. The best way to steep the spots in the solution is to

scrape the spot off the fabric, and to digest it in about a cubic

centimetre of the borax solution, which must not exceed 40°; the

coloured solution may be placed in a little glass cell, with parallel

walls, ·5 centimetre broad, and ·1 deep, and submitted to spectroscopic

examination, either by the ordinary spectroscope or by the

micro-spectroscope; if the latter is used, a very minute quantity can be

examined, even a single drop. In order to interpret the results of this

examination properly, it will be necessary to be intimately acquainted

with the spectroscopic appearances of both ancient and fresh blood.

[48] _Untersuchungen von Blutspuren_ in Maschka’s _Handbuch_, Bd. i.

Halfband 2.

§ 35. =Spectroscopic Appearances of Blood.=--If defibrinated blood[49]

be diluted with water until it contains about ·01 per cent. of

oxyhæmoglobin, and be examined by a spectroscope, the layer of liquid

being 1 centimetre thick, a single absorption band between the wave

lengths 583 and 575 is observed, and, under favourable circumstances,

there is also to be seen a very weak band from 550 to 532. With

solutions so dilute as this, there is no absorption at either the violet

or the red end of the spectrum. A solution containing ·09 per cent. of

oxyhæmoglobin shows very little absorption in the red end, but the

violet end is dark up to about the wave length 428. Two absorption bands

may now be distinctly seen. A solution containing ·37 per cent. of

oxyhæmoglobin shows absorption of the red end to about W.L. 720; the

violet is entirely, the blue partly, absorbed to about 453. The bands

are considerably broader, but the centre of the bands occupies the same

relative position. A solution containing as much as ·8 per cent. of

oxyhæmoglobin is very dark; the two bands have amalgamated, the red end

of the spectrum is absorbed nearly up to Fraunhofer’s line a; the green

is just visible between W.L. 498 and 518. Venous blood, or arterial

blood, which has been treated with reducing agents, such, for example,

as an alkaline sulphide, gives the spectrum of reduced hæmoglobin. If

the solution is equivalent to about ·2 per cent., a single broad band,

with the edges very little defined, is seen to occupy the space between

W.L. 595 and 538, the band being darkest about 550; both ends of the

spectrum are more absorbed than by a solution of oxyhæmoglobin of the

same strength. In the blood of persons or animals poisoned with hydric

sulphide--to the spectrum of reduced hæmoglobin, there is added a weak

absorption band in the red, with its centre nearly corresponding with

the Fraunhofer line C. Blood which has been exposed to carbon oxide has

a distinct spectrum, due, it would seem, to a special combination of

this gas with hæmoglobin; in other words, instead of oxygen, the oxygen

of oxyhæmoglobin has been displaced by carbon oxide, and crystals of

carbon oxide-hæmoglobin, isomorphous with those of oxyhæmoglobin, may be

obtained by suitable treatment. The spectrum of carbon oxide-hæmoglobin,

however, differs so little from that of normal blood, that it is only

comparison with the ordinary spectrum, or careful measurements, which

will enable any person, not very familiar with the different spectra of

blood, to detect it; with careful and painstaking observation the two

spectra are seen to be distinct. The difference between the carbon oxide

and the normal spectrum essentially consists in a slight moving of the

bands nearer to E. According to the measurements of Gamgee, the band α

of CO-hæmoglobin has its centre approximately at W.L. 572, and the band

β has for its centre W.L. from 534 to 538, according to concentration.

If a small quantity of an ammoniacal solution of ferrous tartrate or

citrate be added to blood containing carbon oxide, the bands do not

wholly fade, but persist more or less distinctly; whereas, if the same

solution is added to bright red normal blood, the two bands vanish

instantly and coalesce to form the spectrum of reduced hæmoglobin. When

either a solution of hæmoglobin or blood is exposed to the air for some

time, it loses its bright red colour, becomes brownish-red, and presents

an acid reaction. On examining the spectrum, the two bands have become

faint, or quite extinct; but there is a new band, the centre of which

(according to Gamgee) occupies W.L. 632, but (according to Preyer) 634.

In solutions of a certain strength, four bands may be seen, but in a

strong solution only one. This change in the spectrum is due to the

passing of the hæmoglobin into _methæmoglobin_, which may be considered

as an intermediate stage of decomposition, prior to the breaking up of

the hæmoglobin into hæmatin and proteids.

[49] In this brief notice of the spectroscopic appearances of the blood,

the measurements in wave lengths are, for the most part, after

Gamgee.--_Text-Book of Physiological Chemistry_, London, 1880.

A spectrum very similar to that of methæmoglobin is obtained by treating

ancient blood-stains with acetic acid--viz., the spectrum of _acid

hæmatin_, but the band is nearer to its centre, according to Gamgee,

corresponding to W.L. 640 (according to Preyer, 656·6). The portion of

the band is a little different in alkaline solution, the centre being

about 592. Hæmatin is one of the bodies into which hæmoglobin splits up

by the addition of such agents as strong acetic acid, or by the

decomposing influence of exposure; the view most generally accepted

being that the colouring-matter of the blood is hæmatin in combination

with one or more albuminoid bodies. The hæmatin obtained by treating

blood with acetic acid may be dissolved out by ether, and the ethereal

solution then exhibits a remarkable distinctive spectrum. Hence, in the

spectroscopic examination of blood, or solutions of blood, for

medico-legal purposes, if the blood is fresh, the spectrum likely to be

seen is either that of oxyhæmoglobin or hæmoglobin; but, if the

blood-stain is not recent, then the spectrum of either hæmatin or

methæmoglobin.

The colouring-matter of cochineal, to which alum, potassic carbonate,

and tartrate have been added, gives a spectrum very similar to that of

blood (see “Foods,” p. 82); but this is only the case when the solution

is fresh. The colour is at once discharged by chlorine, while the colour

of blood, although changed in hue, remains. The colouring-matter of

certain red feathers, purpurin-sulphuric acid, and a few other reds,

have some similarity to either the hæmatin or the hæmoglobin spectrum,

but the bands do not strictly coincide; besides, no one would trust to a

single test, and none of the colouring-matters other than blood yield

hæmatin.

The blood in CO poisoning has also other characteristics. It is of a

peculiar florid vermilion colour, a colour that is very persistent,

lasting for days and even weeks.

Normal blood mixed with 30 per cent. potash solution forms _greenish_

streaky clots, while blood charged with CO forms red streaky clots.

Normal blood diluted to 50 times its volume of water, and then treated

successively with yellow ammonium sulphide in the proportion of 2 to 25

c.c. of blood, followed by three drops of acetic acid, gives a grey

colour, while CO blood remains bright red. CO blood shaken with 4 times

its volume of lead acetate remains red, but normal blood becomes

brown.[50]

[50] M. Rubner, _Arch. Hyg._, x. 397.

Solutions of platinum chloride or zinc chloride give a bright red colour

with CO blood; normal blood is coloured brown or very dark brown.

Phospho-molybdic acid or 5 per cent. phenol gives a carmine-coloured

precipitate with CO blood, but a reddish-brown precipitate with normal

blood (sensitive to 16 per cent.).

A mixture of 2 c.c. of dilute acetic acid and 15 c.c. of 20 per cent.

potassic ferrocyanide solution added to 10 c.c. of CO blood produces an

intense bright red; normal blood becomes dark brown.

Four parts of CO blood, diluted with 4 parts of water and shaken with 3

vols. of 1 per cent. tannin solution, become at first bright red with a

bluish tinge, and remain so persistently. Normal blood, on the other

hand, also strikes bright red at first, but with a yellowish tinge; at

the end of 1 hour it becomes brownish, and finally in 24 hours grey.

This is stated to be delicate enough to detect 0·0023 per cent. in air.

If blood be diluted with 40 times its volume of water, and 5 drops of

phenylhydrazin solution be added, CO blood strikes rose-red; normal

blood grey-violet.[51]

[51] A. Welzel, _Centr. med. Wiss._, xxvii. 732-734.

Gustave Piotrowski[52] has experimented on the length of time blood

retains CO. The blood of dogs poisoned by this agent was kept in flasks,

and then the gas pumped out by means of a mercury pump on the following

dates:--

[52] _Compt. Rend. Soc. de Biol._, v. 433.

Date. Content of gas in CO.

Jan. 12, 1892, 24·7 per cent.

„ 20, „ 23·5 „

„ 28, „ 22·2 „

Feb. 8, „ 20·3 „

„ 16, „ 15·5 „

„ 26, „ 10·2 „

March 3, „ 6·3 „

„ 14, „ 4·6 „

„ 22, „ 1·2 „

The same dog was buried on the 12th of January, and exhumed on March

28th, and the gas pumped out from some of the blood; this gas gave 11·7

per cent. of CO; hence it is clear that burial preserves CO blood from

change to a certain extent.

N. Gréhant[53] treated the poisoned blood of a dog with acetic acid, and

found it evolved 14·4 c.c. CO from 100 c.c. of blood.

[53] _Compt. Rend._, cvi. 289.

Stevenson, in one of the cases detailed at p. 67, found the blood in the

right auricle to contain 0·03 per cent. by weight of CO.

(2) =Preparation of Hæmatin Crystals=--(Teichmann’s crystals).--A

portion of the borax solution is diluted with 5 or 6 parts of water, and

one or more drops of a 5 or 6 per cent. solution of zinc acetate added,

so long as a brownish-coloured precipitate is thrown down. The

precipitate is filtered off by means of a miniature filter, and then

removed on to a watch-glass. The precipitate may now be dissolved in 1

or 2 c.c. of acetic acid, and examined by the spectroscope it will show

the spectrum of hæmatin. A minute crystal of sodic chloride being then

added to the acetic acid solution, it is allowed to evaporate to dryness

at the ordinary temperature, and crystals of hæmatin hydrochlorate

result. There are other methods of obtaining the crystals. When a drop

of fresh blood is simply boiled with glacial acetic acid, on

evaporation, prismatic crystals are obtained.

Hæmatin is insoluble in water, alcohol, chloroform, and in cold dilute

acetic and hydrochloric acids. It may, however, be dissolved in an

alcoholic solution of potassic carbonate, in solutions of the caustic

alkalies, and in boiling acetic and hydrochloric acids. Hoppe-Seyler

ascribes to the crystals the formula C₆₈H₇₀N₈Fe₂O₁₀2HCl. Thudichum

considers that the pure crystals contain no chlorine, and are therefore

those of hæmatin. It is the resistance of the hæmatin to decomposition

and to ordinary solvents that renders it possible to identify a certain

stain to be that of blood, after long periods of time. Dr. Tidy seems to

have been able to obtain blood reactions from a stain which was supposed

to be 100 years old. The crystals are of a dark-red colour, and present

themselves in three forms, of which that of the rhombic prism is the

most common (see fig.). But crystals like _b_, having six sides, also

occur, and also crystals similar to _c_.

[Illustration]

If the spot under examination has been scraped off an iron implement the

hæmatin is not so easily extracted, but Dragendorff states that borax

solution at 50° dissolves it, and separates it from the iron. Felletar

has also extracted blood in combination with iron rust, by means of warm

solution of caustic potash, and, after neutralisation with acetic acid,

has precipitated the hæmin by means of tannin, and obtained from the

tannin precipitate, by means of acetic acid, Teichmann’s crystals. A

little of the rust may also be placed in a test tube, powdered ammonium

chloride added, also a little strong ammonia, and after a time filtered;

a small quantity of the filtrate is placed on a slide with a crystal of

sodium chloride and evaporated at a gentle heat, then glacial acetic

acid added and allowed to cool; in this way hæmin crystals have been

obtained from a crowbar fifty days after having been blood-stained.[54]

[54] _Brit. Med. Journ._, Feb. 17, 1894.

(3) =Guaiacum Test.=--This test depends upon the fact that a solution of

hæmoglobin develops a beautiful blue colour, if brought into contact

with fresh tincture of guaiacum and peroxide of hydrogen. The simplest

way to obtain this reaction is to moisten the suspected stain with

distilled water; after allowing sufficient time for the water to

dissolve out some of the blood constituents, moisten a bit of

filter-paper with the weak solution thus obtained; drop on to the moist

space a single drop of tincture of guaiacum which has been prepared by

digesting the inner portions of guaiacum resin in alcohol, and which has

been already tested on known blood, so as to ascertain that it is really

good and efficient for the purpose; and, lastly, a few drops of peroxide

of hydrogen. Dragendorff uses his borax solution, and, after a little

dilution with water, adds the tincture and then Heunefeld’s turpentine

solution, which is composed of equal parts of absolute alcohol,

chloroform, and French turpentine, to which one part of acetic acid has

been added. The chloroform separates, and, if blood was present, is of a

blue colour.

§ 36. To prove by chemical and physical methods that a certain stain is

that of blood, is often only one step in the inquiry, the next question

being whether the blood is that of man or of animals. The

blood-corpuscles of man are larger than those of any domestic animal

inhabiting Europe. The diameter of the average red blood-corpuscle is

about the 1/126 of a millimetre, or 7·9 µ.[55] The corpuscles of man and

of mammals, generally speaking, are round, those of birds and reptiles

oval, so that there can be no confusion between man and birds, fishes or

reptiles; if the corpuscles are circular in shape the blood will be that

of a mammal. By careful measurements, Dr. Richardson, of Pennsylvania,

affirms that it is quite possible to distinguish human blood from that

of all common animals. He maintains, and it is true, that, by using very

high magnifying powers and taking much trouble, an expert can

satisfactorily identify human blood, if he has some half-dozen drops of

blood from different animals--such as the sheep, goat, horse, dog, cat,

&c., all fresh at hand for comparison, and _if the human blood is

normal_. However, when we come to the blood of persons suffering from

disease, there are changes in the diameter and even the form of the

corpuscles which much complicate the matter; while, in blood-stains of

any age, the blood-corpuscles, even with the most artfully-contrived

solvent, are so distorted in shape that he would be a bold man who

should venture on any definite conclusion as to whether the blood was

certainly human, more especially if he had to give evidence in a

criminal case.

[55] 1/3200 of an inch; the Greek letter µ is the micro-millimetre, or

1000th of a millimetre, ·00003937 inch.

Neumann affirms that the pattern which the fibrin or coagulum of the

blood forms is peculiar to each animal, and Dr. Day, of Geelong, has

independently confirmed his researches: this very interesting

observation perhaps has not received the attention it merits.

When there is sufficient of the blood present to obtain a few milligrms.

of ash, there is a means of distinguishing human blood from that of

other common mammals, which has been neglected by authorities on the

subject, and which may be found of real value. Its principle depends

upon the relative amounts of potassium and sodium in the blood of man as

compared with that in the blood of domestic animals. In the blood of the

cow, sheep, fowl, pig, and horse, the sodium very much exceeds the

potassium in the ash; thus the proportion of sodium oxide to that of

potassium oxide in the blood of the sheep is as K₂O ·1 : Na₂O ·6; in

that of the cow, as 1 : 8; in that of the domestic fowl, as 1 : 16;

while the same substances in human blood are sometimes equal, and vary

from 1 : 1 to 1 : 4 as extremes, the mean numbers being as 1 : 2·2. The

potassium is greater in quantity in the blood-corpuscles than in the

blood serum; but, even in blood serum, the same marked differences

between the blood of man and that of many animals is apparent. Thus, the

proportion of potash to soda being as 1 : 10 in human blood, the

proportion in sheep’s blood is 1 to 15·7; in horse’s serum as 1 to 16·4;

and in the ox as 1 to 17. Since blood, when burnt, leaves from 6 to 7

per thousand of ash, it follows that a quantitative analysis of the

relative amounts of potassium and sodium can only be satisfactorily

effected when sufficient of the blood is at the analyst’s disposal to

give a weighable quantity of mineral matter. On the other hand, much

work requires to be done before this method of determining that the

blood is either human, or, at all events, not that of an herbivorous

animal, can be relied on. We know but little as to the effect of the

ingestion of sodium or potassium salts on either man or animals, and it

is possible--nay, probable--that a more or less entire substitution of

the one for the other may, on certain diets, take place. Bunge seems in

some experiments to have found no sodium in the blood of either the cat

or the dog.

The source from which the blood has emanated may, in a few cases, be

conjectured from the discovery, by microscopical examination, of hair or

of buccal, nasal, or vaginal epithelium, &c., mixed with the

blood-stain.

Poisons, Their Effects and Detection A Manual for the Use of Analytical Chemists and Experts · 第 2 / 23 章