And you judged from the application of chemical tests?—Yes, Sir.
Be so good as to state what the chemical tests were which you used?—The first was with the sulphate of copper, which is the common blue vitriol. If you put a little carbonate of potash into water containing a solution of arsenic, and then add the sulphate of copper in solution, a green precipitate will be produced; whereas, if no arsenic be present, a blue precipitate would be formed: that was the first test which I used.
What was the second test?—The second test was with the nitrate of silver, or common lunar caustic, (these are the same in substance, but the lunar caustic is the more common term). Put a little carbonate of potash into water containing arsenic in solution, and dip the end of a cylindrical piece of lunar caustic into the water, a yellow precipitate will be produced; whereas if no arsenic be present, a white precipitate would be formed. Those were the chief tests which I used; but in order to ascertain whether any thing which had been taken into the stomach, or was naturally contained in it, would alter the appearances produced by the tests, so as to make the result uncertain, I tried other experiments. I concluded that bile formed part of the contents of the stomach; I therefore procured some and mixed it with water, and subjected it to the same tests in the same manner, and I found that the appearance of the precipitate was not the same as if arsenic were present; I therefore inferred that bile, in the quantity in which it may occasionally be found in the stomach, would not alter the conclusion I had drawn from the result of my first experiments.—I was informed that Mrs. Downing had eaten onions; I boiled some in water in the usual way, and after pouring off the water in which they were boiled, I poured some boiling water on them, and let them stand for some hours; I then ascertained what effect this water would produce on the tests, and was satisfied that it would not, when the experiment was carefully made, produce the ap-
