26 ESSAY ON THE RATIONAI-E OF 



poisonous matter into gravy. Dr. Christison was of opinion that 

 all the symptoms might have been produced by natural means ; and 

 was led to suppose that poison had been swallowed merely from the 

 circumstance of two persons being taken ill nearly at the same 

 time, after partaking of the same food, and with symptoms which 

 various kinds of poisons would produce. In answer to questions by 

 the court, he said the probability was greatly strengthened by the 

 fact that the violence of the symptoms was in proportion to the 

 quantities of the suspected food taken.* The prisoner admitted that 

 she had introduced a little powder, but declared that it was only for 

 a bit of fun, and not to do harm, but merely to sicken the parlies. 

 This question was the subject of much discussion in the celebrated 

 case of Castaing. But, upon general principles, it cannot be doubt- 

 ed that courts of law would require chemical evidence of the poison, 

 ing to be adduced wherever it were attainable ; and it is believed 

 that no modern case of satisfactory conviction can be adduced where 

 there has not been such evidence or, in its absence, the equivalent 

 evidence of confession. The following remarkable case is highly 

 instructive in relation to this important question. 



JRobert Sawle Donnall, a surgeon and apothecary, of Falmouth, 

 was tried at the spring assizes, 1817, at Launceston, before Mr. 

 Justice Abbott, for the murder of Mrs. Elizabeth Downing, his mo- 

 ther-in-law. The prisoner and the deceased were next-door neigh- 

 bours, and lived upon friendly terms ; and there was no suggestion 

 of malice, nor could any motive be assigned which could have in- 

 duced the prisoner to commit such an act, except that he was in 

 somewhat straightened circumstances, and in the event of his mo- 

 ther-in-law's death would have become entitled to a share of her 

 property. On the 19th of October the deceased drank tea at the 

 prisoner's house, and returned home much indisposed, retching and 

 vomiting, with a violent cramp in her legs, from which she did not 

 recover for several days. On Sunday, the 3rd of November, after 

 returning from church, she dined at home on boiled rabbits smo- 

 thered with onions, and, upon the invitation of her daughter, drank 

 tea in the evening at the prisoner's honse, with a family pai'ty. 

 The prisoner handed to the deceased cocoa and bread and butter; 

 and while she was drinking the second cup she complained of sick- 

 ness and went home, where she was seized with retching and vomit- 

 ing, attended with frequent cramps, and then a violent purging took 

 place, and at eight o'clock the next morning she died. The nervous 



" Rex V, Mary Ann Alcorn, Syme's Justiciary Reports, vol. i., p. 221. 



