The professional poisoner in India--for there are many such--is rarely caught or even suspected. In a large number of cases, crimes of this kind are taken little notice of by the community; and sometimes the poisoner apparently thinks nothing of poisoning a whole family in order to make sure of his victim. The utter absence of motive in the majority of cases would point to the conclusion that they were largely the result of homicidal mania. For more than a century after the properties of arsenic were well known, there was no certain method known for its detection, and very little advance was made until the early part of last century, when Marsh discovered his test in 1836, by means of which the minutest quantities of the poison may be detected. It is characteristic of both arsenic and mercury, that their presence may be proved and demonstrated, even in the bones, years after they have been taken. In proof of this, the following remarkable case is given. A wealthy farmer died, and was buried in the tomb where his father had been interred thirty-five years before. An examination of certain of the bones of the father revealed particles of a metallic-looking substance, which was collected and tested, and proved to be mercury. It had thus been preserved in his body for more than the third of a century, the probability being, that he had been in the habit of taking it medicinally during the latter part of his life. Another strange case came under the notice of a Bristol chemist, in which he found abundant traces of arsenic in the bodies of several young children after they had been buried eight years.