28 ESSAY ON THE HATIONALE OF 



to neutralize and explain away the circumstances of presump- 

 tion against the prisoner, by shewing, first, that the symptoms and 

 morbid appearances, though they were such as might and did com- 

 monly denote poisoning, did not exclude the supposition that they 

 might also have been occasioned by cholera morbus, or some other 

 cause ; secondly, that no valid reason existed why, if arsenic had been 

 contained in the contents of the stomach, it had not been reproduced 

 in the metallic state, either by an original experiment, or by experi- 

 ments on the matter to which the other tests had been applied ; 

 thirdly, that the dilution of the contents of the stomach had not ren- 

 dered the experiment of reduction impracticable, but only more 

 dilatory and troublesome ; and, fourthly, that the tests actually 

 resorted to were fallacious, and produced the same appearances upon 

 application to innocent matter, namely, the sulphate of copper pro- 

 ducing the green, and the nitrate of silver producing the yellow pre- 

 cipitate, on being applied to an infusion of onions. It was in vain to 

 urge that a decoction of onions was not the same thing as that parti- 

 cular preparation of onions of which the deceased had partaken, and 

 that, in the hands of the witness for the prosecution, this experiment 

 had been attended with a different result ; the facts adduced by the 

 prisoner's witnesses conclusively proved that the appearances produced 

 by the tests employed might be produced by some other cause than 

 the presence of arsenic, and therefore that the tests were fallacious, 

 and that an infallible test might have been resorted to. Thus every 

 one of the grounds of presumption against the prisoner were succes- 

 sively destroyed, so that the case was left without any substantial 

 foundation ; though the conduct of the prisoner had naturally created, 

 and must necessarily leave, strong and well-founded impressions un- 

 favourable to the belief of his innocence. 



The chemical evidence brought forward in the case of Mary Ann 

 Burdock, who was convicted at the Bristol Spring Assizes, 1835, of 

 the murder of Mrs. Clara Ann Smith by poison, presents an instruc- 

 tive contrast with that adduced in the last-mentioned case : the mo- 

 ral evidence was also strong. The deceased, a widow, about sixty 

 years of age, was possessed of considerable property in money, and 

 had for several years lived in lodgings at various places, and ulti- 

 mately went to lodge with the prisoner, who kept a lodging-house in 

 Bristol. In October, 1833, the deceased became indisposed from a 

 cold ; and in the evening of the 26th of that month the prisoner gave 

 her some gruel, into which she had been observed, by a young woman 

 hired to wait on the deceased, to put some pinches of yellow powder, 



