As applied to criminal cases this definition is obviously open to criticism, for it is applicable to a substance such as coffee which, when taken in excess, will "seriously affect the health." Some reference to the quantity is therefore needed. A drug, such as morphia, may be of benefit when given in small doses, but becomes a poison when given in large quantity. In the case of Cluderay, however, it could hardly be contended that the administration of entire coculus pods, although not producing injurious results, could in any way be beneficial.
The trial of Tawell at the Aylesbury Assizes in 1845, on the charge of murdering Sarah Hart at Slough, presented several points of scientific interest.
The manner in which the electric telegraph was employed in effecting his capture has been described in another place.
At the trial Tawell denied that he had ever been to Slough at all, but the woman who had heard the screams of the victim had seen and spoken with him, and swore positively to his identity.
It was proved that on the day of the murder Tawell had bought some Scheele's prussic acid in London, but he accounted for this by the fact that he was constantly in the habit of buying the poison for external use.
In the cottage, where the woman was found lying dead when the doctor arrived, were two empty tumblers and a bottle of porter, while a small amount of prussic acid was found in the stomach of the woman.
The counsel for the defence urged that there was no proof that the woman had died from the effects of prussic acid and that some sudden emotion might have been the cause of death.
As to the prussic acid found in the body, he suggested that it might have been derived from apple-pips eaten by the deceased.
Chemical evidence, however, was brought forward to prove that prussic acid could not have been formed as suggested in the process of digestion, and the only result of this novel defence was that for long afterwards the barrister was known as "Apple-pip Kelly."
In his summing up of the evidence the judge, Baron Parker, said with reference to one of the contentions of the prisoner's counsel: "If the evidence satisfies you that the death was occasioned by poison, and that poison was administered by the prisoner it is not necessary to give direct and positive proof of what is the quantity which would destroy life, nor is it necessary to prove that such quantity was found in the body of the deceased, if the other facts lead you to the conclusion that the death was occasioned by poison and that it was knowingly administered by the prisoner."