This substance is so rarely met with as to be an object of little
consequence to the medical jurist: nevertheless I have found in the
course of reading two instances of poisoning with it. A very dangerous
and tedious case has been related by Professor Bernt, which arose from
too great a quantity having been given medicinally by an ignorant
druggist;[557] and a case of accidental poisoning with it has been
related in the London Medical Repository.[558] A singular account too
has been published of the accidental poisoning of seven horses with it
at Paris. They all died, most of them with the symptoms and morbid
appearances of well-marked inflammation of the alimentary canal.[559]
When solid it forms tetraedral prismatic crystals, acuminated by four
planes. It is very soluble in water, fuses at a red heat, and on cooling
concretes into a crumbly, foliaceous mass, having a pearly lustre. It is
easily known by the effect of the process of reduction—of the nitrate of
silver, the salts of copper, and sulphuretted-hydrogen. Heated with
charcoal in a tube it gives off metallic arsenic in the usual manner;
but a stronger heat is required than for the reduction of the arsenious
acid. Dissolved in water and treated with nitrate of silver it yields a
brick-red precipitate, the arseniate of silver. With the salts of copper
its solution gives a pale bluish-white precipitate, the arseniate of
copper. With sulphuretted-hydrogen gas, preceded by acidulation with
muriatic acid, and transmitted for a considerable length of time, it
yields the yellow sulphuret of arsenic. When in solution it yields
arsenic both by Reinsch’s process and the method of Marsh.