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).
Section 22. “Whosoever shall unlawfully apply or administer to or cause to be taken by, or attempt to apply or administer to, or attempt to cause to be administered to or taken by, any person, any chloroform, laudanum, or other stupefying or overpowering drug, matter, or thing, with intent, in any of such cases, 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.”
Section 23 enacts that, “Whosoever shall unlawfully administer to, or cause to be administered to, or 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 a felony.”
Section 24. “Whosoever shall unlawfully or maliciously administer to or cause to be administered to or taken by any other person any poison or other destructive or noxious thing with intent to injure or aggrieve or annoy such person shall be guilty of a misdemeanour.”
Section 25. “If upon the trial of any person charged with the felony above mentioned the jury shall not be satisfied that such person is guilty thereof, but shall be satisfied that he is guilty of the misdemeanour above mentioned, then, and in every such case, the jury may acquit the accused for such felony and find him guilty of a misdemeanour.”