Page:Treatise on poisons in relation to medical jurisprudence, physiology, and the practice of physic (IA treatiseonpoison00chriuoft).pdf/358

 1592 among the senators of Bern, and a number of their guests who had been invited to a great entertainment, was supposed to have arisen from a poisonous impregnation of this kind. The wine used at the feast had been kept cool in copper vessels immersed in a very cold well. Many of the company were attacked with dysenteric symptoms, and some died.

Vinegar also dissolves metallic copper. Dupuytren observed that the vinegar sold by hawkers in the streets of Paris generally contained copper from the action of the acetic acid on the stop-cocks of the little vessels used in retailing it. Others in like manner have found copper in vinegar pickles prepared in copper vessels. Thus Dr. Percival found a strong impregnation of copper in pickled samphire, of which a young lady ate one morning two breakfast platefuls, and which proved fatal to her in nine days. And Dr. Falconer once detected so large a quantity in some pickled cucumbers bought at a great London grocer's, that it was deposited on a plate of iron, and imparted its peculiar taste and smell to the pickles. It seems indeed to have been at one time the custom to make a point of adulterating pickles with copper; for in many old cookery-books the cook is told to make her pickles in a copper pan, or to put some halfpence among the pickles to give them a fine green colour.

The action of the vegetable acids, and more particularly of vinegar on copper, depends on the co-operation of the atmospheric air held in solution by the fluid, and in contact with its surface. Without such co-operation the copper cannot be oxidated. This fact, which was determined experimentally by Proust, will explain the observations of Eller and Falconer,—that it is not dangerous to boil acidulous liquids in copper vessels, while it is very unsafe to keep these fluids cold in the same vessels. In the latter instance the liquid is impregnated with atmospheric air, while in the former the usual aëriform contents are driven off by the heat. I must observe, however, in limitation of Proust's statement, that strong vinegar, such as the pyroligneous acetic acid, will become impregnated to a certain extent if boiled in copper vessels. The action which takes place is the same as that remarked by him in the case of cold vinegar:[F] the copper where it is always covered remains quite bright; but at the edge of the fluid it becomes oxidated, and the oxide is dissolved by the occasional bubbling up of the acid.

In the last place, the property of oxidating and uniting with copper is likewise possessed by fatty matters and oils. According to Falconer, fatty substances do not act on metallic copper unless they are rancid. But Proust is probably more correct when he states, that they will act, though fresh, provided they are aided by the co-*operation of atmospheric air. I have found, that, if a plate of cop-*