The London Art of Cookery, and Housekeeper’s Complete Assistant; On a New Plan, Made Plain and Easy to the Understanding of every Housekeeper, cook, and servant in the Kingdom. … To Which is Added, an Appendix, containing Considerations on Culinary Poisons; Directions for making Broths, &c. for the Sick; a List of Things in Season in the different Months of the Year; Marketing Tables, &c. &c. Embellished with A Head of the Author, and a Bill of Fare for every Month in the Year, elegantly engraved on Thirteen Copper-plates. By John Farley, Principal Cook at the London Tavern. The Seventh edition With the Addition of many new and elegant Receipts in the various Branches of Cookery. London: Printed for J. Satcherd and J. Whitaker, No. 12, B. Law, No. 13, Ave-Maria-Lane; and G. and T. Wilkie, St. Paul’s Church-Yard, 1792.
APPENDIX. Section I. Considerations of Culinary Poisons.
Though we have already, in different parts of this work, occasionally reminded the houskeeper and cook of the fatal consequences attending coppers and saucepans not being properly tinned, yet we shall here enter on a particular enquiry into the nature and property of culinary poisons, for the information and satisfaction of those who may wish to have a more perfect knowledge of such matters.
By the use of copper vessels for dressing our food, we are daily exposed to the danger of poison; and even the air of a kitchen, abounding with oleaginous and saline particles, disposes those vessels to dissolution before they be used. Copper, when handled, yields an offensive smell; and if touched with the tongue, has a sharp pungent taste, and even excites a nausea. Verdigrise is nothing but a solution of this metal by vegetable acids; and it is well known, that a very small quantity of this solution will produce cholics, vomitings, intolerable thirst, universal convulsions, and other dangerous symptoms. If these effects, and the prodigious divisibility of this metal be considered, there can be no doubt of its being a violent and subtle poison. Water, by standing some time in a copper vessel, becomes impregnated with verdigrise, as may be demonstrated by throwing into it a small quantity of volatile alkali, which will immediately tinge it with a paler or deeper blue, in proportion to the rust contained in the water. Vinegar, apple-sauce, greens, oil, grease, butter, and almost every other kind of food, will extract the verdigrise in a great degree. Some people imagine, that the ill effects of copper are prevented by its being tinned, which, indeed, is the only preventative in that case; but the tin, which adheres to the copper, is so extremely thin, that it is soon penetrated by the verdigrise, which insinuates itself through the pores of that metal, and appears green upon the surface.
Verdigrise is one of the most violent poisons in nature; and yet, rather than quit an old custom, the greater part of mankind is content to swallow some of this poison every day. Our food receives its quantity of poison in the kitchen, by the use of copper pans and dishes; the brewing mingles poinson in our beer, by boiling it in copper; salt is distributed to the people from copper scales, covered in verdigrise; our pickles are rendered green by the infusion of copper; the pastry-cook bakes our tarts in copper patty-pans; but confections and syrups have greater powers of destruction, as they are set over a fire in copper vessels which have not been tinned, and the verdigrise is plentifully extracted by the acidity of the composition. After all, though we do not swallow death in a single dose, yet it is certain, that a quantity of poison, however small, which is repeated with every meal, must produce more fatal effects than is generally believed.
Bell-metal kettles are frequently used in boiling cucumbers for pickling, in order to make them green; but this is a practice as absurd as it is dangerous. If the cucumbers acquire any additional greeness by the use of these kettles, they can only derive it from the copper, of which they are made; and this very reason ought to be sufficient to overturn so dangerous a practice.