GREEN CARBONATE OF COPPER—_Natural Verdegris_. This substance forms spontaneously on surfaces of copper and brass; it differs from the oxide in its green colour, and in effervescing with dilute sulphuric acid; with ammonia, however, it demeans itself in the same manner, and is likewise insoluble in water. It is poisonous. From the above history of these substances the medical practitioner will easily perceive under what circumstances, and by what bodies, metallic vessels of copper may be rendered dangerous. The oxide and carbonate, formed in them, will easily dissolve in acidulous and oily aliments, whence it follows that all preparations of such food, if conducted in vessels whose surfaces have contracted this change will be liable to prove deleterious.[309] If the vessels be perfectly clean, acid preparations may be safely boiled in them, but they must be poured out immediately, and not suffered to remain sufficiently long to allow the copper to become oxidized. To the formation of the oxide of copper, and to the acetic acid contained in the wine, vinegar, beer, and cider, _M. Orfila_ attributes the production of the _acetate_ which forms about the corners of the cocks in vessels containing these liquors. Upon the same principle the _soda water_ sold in this town, in a draught, from the pump, is liable to metallic impregnation, as we have fully satisfied ourselves. Equally important is it for the forensic physician to be acquainted with the various other sources from which copper poison may be derived. In consequence of the fact of the oxide of copper forming, with the acids, compounds of a beautiful green colour, the metal is often employed in cookery to impart a vivid hue to various articles; the sale of pickles, for instance, frequently depends upon the liveliness of their green colour; whence we find, in works[310] on cookery, directions for ensuring such an effect, by boiling the pickles with copper coin, or by suffering them to stand for some time in vessels of that metal. In the third volume of the _Medical Transactions of the College of Physicians_ we shall find an interesting history, related by _Dr. Percival_ of Manchester, of a young lady who amused herself, whilst under the hands of the hair-dresser, with eating pickled samphire, of which she consumed two breakfast plates full; she shortly afterwards complained of great thirst, pain in the stomach, and a rash appeared upon her hands and breast. After an illness of nine days, during which she suffered severe vomitings, and tormina of the bowels, she expired. Upon examining the samphire, _Dr. Percival_ found that it was very strongly impregnated with copper. In the preparation of confectionary, especially sugar-plums, and sweatmeats of a green colour, copper is very generally introduced, and many instances are recorded of their having proved highly deleterious. Catsup is also said to be occasionally impregnated