Copper cooking utensils are attended with so much danger, that the use of them ought to be laid entirely aside. They have not only occasioned many fatal accidents, (which have been made public), but they have injured the health of great numbers, where the slower, but not less dangerous effect has not been observed. If not kept very clean and bright, they become covered with verdigris, for all fat, oily, or buttery substances corrode copper; and if they are kept clean and bright, the rubbing or scraping that takes place when making stews, or cooking dishes that require stirring, and remaining a considerable time on the fire, always wears off some of the metal which impregnates the food, and has a deleterious effect. The inexcusable negligence of persons who make use of copper vessels has been productive of mortality, so much more terrible, as they have exerted their action on a great number of persons at once. Though, after all, a single dose be not mortal, yet a quantity of poison, however small, when taken at every meal, must produce more fatal effects than are generally apprehended; and different constitutions are differently affected by minute quantities of substances that act powerfully on the system. Some years ago, the death of several persons was occasioned, at Salt-hill, by the cook sending a ragout to the table which she had kept from the preceding day in a copper vessel, badly tinned. Another instance of death occasioned by the eating of pickles, prepared in copper vessels, is mentioned by Dr. Percival.[41] [41] See a Treatise on the Adulteration of Food and Culinary Poisons, and Methods of Detecting them, p. 249. Dr. Johnson gives an account of the melancholy catastrophe of three men being poisoned, after excruciating sufferings, in consequence of eating food cooked in an unclean copper vessel, on board the Cyclops frigate; and, besides these, thirty-three men became ill from the same cause. If, however, copper utensils are to be used, they should be employed with the precautions as used in France, where the tinning of the vessels on the inside is done as regularly as the shoeing of horses in a farm-yard.--If the least occasion is thought to exist, the vessel is immediately tinned; but to prevent all risk, it is generally done _once a month_ with stew-pans that are in daily use. Moreover, the victuals are never stirred with any thing of metal, but with a wooden spoon, or flat stick made for the purpose. The following wholesome advice on this subject is given to cooks by Dr. Kitchiner.