Of the process employed in tinning in ancient times, we have no account; but the words of Pliny _incoquere_ and _incoctilia_ seem almost to denote that it was performed, as in tinning our iron wares, by immersing the vessels in melted tin. It appears also to have been done at an early period in a very perfect manner, both because the tinned articles, as Pliny says, could scarcely be distinguished from silver, and because the tinning, as he adds, with an expression of wonder, did not increase the weight of the vessels. The metal, therefore, was applied so thin that it could make no perceptible addition to the weight. This is the case still, when the work has been skilfully executed; and it affords a remarkable proof of the astonishing divisibility of metal. Dr. Watson caused a vessel, the surface of which contained 254 square inches, and which weighed twenty-six ounces, to be tinned, and found that the weight was increased only half an ounce; consequently half an ounce of tin was spread over 254 square inches. But, notwithstanding all this dexterity, which must be allowed to the Romans, they appear to have employed tinning at any rate for kitchen utensils and household furniture very seldom. It is scarcely ever mentioned, and never where one might expect it, that is to say, in works on cookery and domestic œconomy, where the authors give directions for preparing and preserving salt provisions. When they speak of the choice of vessels, they merely say that new earthen ones should be employed. Some of the physicians only have had the foresight to recommend tinned vessels. It does not appear indeed that the Romans, though copper vessels were in general use among them, employed any precautions to prevent them from being injurious to the health. Pliny only says that a coating of _stannum_ improved the taste of food, and guarded against verdigris. The former part is to be thus understood; that the bad taste occasioned by copper was prevented; but he does not say that the health was secured by it. The term also _incoctilia_, usual in the time of Pliny, is found in his works alone. It is likewise remarkable, that among the numerous vessels found at Herculaneum, as I have already remarked, the greater part of them were of copper or _stannum_, few of which were silvered, and none tinned. Had tinning been then as much used as at present, some tinned vessels must have been found.