SECTION II. Toxicology

TOXICOLOGY

CHAPTER I

DEFINITION OF A POISON--SALE OF POISONS--CLASSIFICATION OF POISONS--ACTION OF POISONS--GENERAL EVIDENCE OF POISONING--GENERAL TREATMENT IN CASES OF POISONING --GENERAL METHODS OF EXAMINATION FOR POISON

Toxicology is that division of Forensic Medicine which takes into consideration the modes and actions of poisons upon the living body, the treatment of their effects upon the body, and the methods of detecting them when occasion requires.

=Definition of a Poison.=--Neither the law nor medicine defines a poison. The popular definition is to be avoided, viz., that, a poison is a substance capable of acting injuriously on the body when taken or administered in a small dose.

Husband defined a poison as “any substance which, introduced into the system or applied to the body, is injurious to health and destroys life, irrespective of temperature or mechanical means.”

Taylor and Stevenson define a poison as “a substance which when absorbed into the blood is, by its direct action, capable of seriously affecting health or destroying life.”

There are substances, however, which do not require absorption into the blood in order to exert their deleterious action, e.g. the corrosive acids and alkalies; but, although the chief action is a local one in most cases, some absorption does take place and is evidenced in systemic effects, and are so classified as poisons differing from powdered glass, which acts mechanically only and is not a poison in the true sense of the word.

Winter Blyth considers that “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.”

According to Luff a poison is “a substance which, either by its direct action upon the skin or mucous membranes, or after its absorption into the blood, is capable of injuriously affecting health or destroying life.”

Letheby defines a poison as “anything which otherwise than by the agency of heat or electricity is capable of destroying life, either by chemical action on the tissues of the living body, or by physiological action from absorption into the system.”

The law does not recognise the manner in which the substance acts, nor the result; the legal standpoint is the intent of the administrator qua administrator. The law is as follows: “Whosoever shall administer or cause to be administered or taken by any person any poison or other destructive thing with intent to commit murder shall be guilty of a felony” (24 and 25 Vict. c. 100, sec. 11).