very near the truth. But as the quantity operated on in this instance formed only 51 parts out of the 180 of the whole volume of the contents of the bottle as it was first brought to me, the following proportion will show how much was contained in the whole. For if 51 parts give 1·43 grains of cyanide of silver, 180 parts will give 5·047 grains of cyanide of silver. This quantity of cyanide of silver is equivalent to 1·002 grains of real hydrocyanic or prussic acid, which is equal to 50 grains of the prussic acid of the strength of the London Pharmacopeia. The determination of the relative quantity operated on, and the original volume of the contents of the stomach, was ascertained by measuring, with water, the bottle filled, as near as possible to remember, to that part in the neck where the contents originally stood, which was 180½ drachms, and to the mark made by the file 51½ drachms. “I may also remark that the contents of the stomach, after distillation, was still strongly acid, occasioned most probably by the acid in the beer, and also by the acid which is invariably produced during the process of digestion.”[13] During his _examination, Mr. Cooper_ produced the bottles containing the Prussian blue produced from the stomach and from the apple-pips—the former dark blue in colour, the latter hardly more than tinged with it. When placed side by side on the front of the witness-box the marked contrast caused much excitement in Court. The _cross-examination_ of this witness by _Mr. Kelly_ was so important, that though very lengthy it is necessary to give it in considerable detail. “Until this case,” said the witness, “I had never examined the contents of a human stomach where a person had been killed by prussic acid, or a human stomach containing prussic acid. Respecting the effect of prussic acid on the stomach and tissues of the body, my knowledge is only theoretical. Prussic acid, which I have smelt from its most concentrated to its weakest state, has a peculiar smell; it affects different persons differently. When I smell it, it affects spasmodically the back of the throat. But it loses its smell in combinations. I am not aware what quantity of prussic acid destroys life. I have no practical knowledge on the subject. The case I am most familiar with is that of the seven epileptics. “I began my investigation with the view of seeing if oxalic acid was present. I recognised the odour of beer more strongly in the contents of the stomach than anything else. I did not trace the smell of prussic acid in them, nor feel any spasmodic affection in the throat in smelling them. I did not come to the conclusion, after trying for those acids and mercurial poisons, which I did not discover, that there was prussic acid in the stomach, but I remarked to those present at that time, ‘Well, if this person has taken poison, it must be prussic acid.’