To the Lord Advocate.—“In administering large doses of arsenic many vehicles are excluded. Cocoa or chocolate is a vehicle in which a large dose might be given. There is a great difference between giving rise to suspicion and actual detection. I have found by actual experiment, that when 30 to 40 grains of arsenic are put into a cup of warm chocolate, a large portion of the arsenic settles down in the bottom of the cup, and I think a person drinking such poisonous chocolate would suspect something when the gritty particles came into his mouth; but when the same and even a larger quantity were boiled with the chocolate, instead of being stirred or mixed, none of it settles down.[108] I could not separate the soot from Murdoch’s arsenic, but a very large quantity of it might be separated. Supposing a person subjected to repeated doses of arsenic, I have no evidence on which to form an opinion whether the last dose would be more rapidly fatal.”
To the Dean.—“In the case of chocolate being boiled with arsenic in it, a larger portion dissolves and does not subside. That is what I find by actual experiment. Coffee or tea could not be made the vehicle of so large a dose of arsenic.”
To the Lord Justice Clerk.—“The period in which the arsenic produces its effect varies in different individuals, and according to the mode of administration. Pain in the stomach is one of the first symptoms, and vomiting usually accompanies the pain, but it may be very severe before the vomiting actually begins. Ten, fifteen, or twenty grains might be given in coffee.”
Professor Penny, subsequently (on the fourth day), gave the following account of experiments made by him with arsenic purchased from Murdoch’s and Currie’s shops:—
“Some of the arsenic I purchased from Murdoch’s, which was mixed with soot, I gave to a dog, and I had no difficulty in detecting the soot in the stomach of that dog after death. I administered arsenic, coloured by myself with indigo, to another dog, and had no difficulty in detecting the indigo in that case by chemical tests. To another dog I administered arsenic purchased at Currie’s, which it will be remembered was mixed with indigo. After death I detected black particles in the stomach of that dog, but I could not undertake to identify the arsenic found with the arsenic given: I mean I found carbonaceous particles, but that I could not undertake to say that these particles were of themselves sufficient to identify any of the particular poison administered. But as I administered it myself, it must have been the same—at least, I know of no other source. I could detect no arsenic in the brains of the dogs. I found solid arsenic in the stomach, as well as in the texture of the stomach.”
By the Court.—“Is it the fact that there is less arsenic found in the brains of animals than of human beings?”
Witness.—“I am not aware. In the one case I detected blue colouring matter of indigo, in the other carbonaceous particles.”[109]
By the Dean.—“Did you make yourself acquainted with the nature of the colouring matter of Currie’s arsenic before administering it to the dog?”