- tion of vessels for culinary and other domestic purposes, or ignorantly
resorted to by confectioners and others to impart a good colour to sweatmeats and preserves. Such accidents have been materially diminished in frequency since the poisonous qualities of the metal, and the circumstances under which it is acted on by articles of food, have become known. Nevertheless they are still frequent enough. The diffusion among the common people of the knowledge of the properties of copper has also naturally led some persons to have recourse to its preparations for the purpose of self-destruction. Poisoning with copper has seldom been caused by the wilful act of another person; for the deep colour of its compounds and their strong disagreeable taste render it a difficult matter to administer them secretly. This, however, though difficult, is not impossible: whatever may be swallowed accidentally, may be also administered secretly. In 1795 a woman Inglis was tried at Aberdeen for administering sulphate of copper with intent to poison; but the charge was not proved.[1] In 1842 an attempt was made at Béziers in France to poison a young woman by dissolving this salt in her coffee; but the first mouthful caused such a sense of constriction in the throat as to apprize her of something deleterious being present, and she escaped after suffering from soreness of the mouth, vomiting and cramps.[2] A case of imputed poisoning with sulphate of copper has been related at page 76.
Section I.—Of the Chemical History and Tests of the Preparations of Copper.
Metallic copper has a special red colour, to which it gives its own name. Its specific gravity is nearly 9, its hardness considerable, its tenacity great, its point of fusion about 27° W. or at a full-white heat.
It unites with oxygen in two proportions, forming a yellowish-red protoxide, and a peroxide, which, when dry, is brownish-black—when hydrated, azure-blue. It unites also with sulphur in two corresponding proportions, forming a gold-yellow proto-sulphuret, the natural copper-pyrites, and a black bisulphuret, which is formed by sulphuretted-hydrogen in all the solutions of this metal. The peroxide unites with ammonia. The acids all unite with the oxide and form blue or green salts, some of which are soluble, some insoluble. The oxide is frequently mixed with other matters to form various pigments; but in such compounds the union is generally mechanical, not chemical. Of the substances thus formed and existing in nature and the arts the following only require notice here. 1. Mineral green, and other pigments formed with the hydrated oxide. 2. Natural verdigris, or the carbonate. 3. Blue vitriol, or the sulphate. 4. Artificial verdigris, or the mixed acetates. 1. Mineral Green.
The description of this substance and its chemical properties must
