Mr. Hendrie, in his notes to the third book of the “Schedula diversarum artium” of Theophilus, says that the ancients had a method of softening and bending ivory by immersion in different solutions of salts in acid. “Eraclius has a chapter on this. Take sulphate of potass, fossil salt, and vitriol; these are ground with very sharp vinegar in a brass mortar. Into this mixture the ivory is placed for three days and nights. This being done, you will hollow out a piece of wood as you please. The ivory being thus placed in the hollow you direct it, and will bend it to your will.” The same writer gives another recipe from the Sloane manuscript (of 15th century), no. 416. This directs that the ingredients above mentioned “are to be distilled in equal parts, which would yield muriatic acid, with the presence of water. Infused in this water half a day, ivory can be made so soft that it can be cut like wax. And when you wish it hardened, place it in white vinegar and it becomes hard.” Sir Digby Wyatt, in a lecture read before the Arundel society, quotes these methods from Mr. Hendrie and adds another from an English manuscript of the 12th century: “Place the ivory in the following mixture. Take two parts of quick lime, one part of pounded tile, one part of oil, and one part of torn tow. Mix up all these with a lye made of elm bark.” These various recipes have been tried in modern days, and the experiments, hitherto, have completely failed. Considerable variety of colour will be observed in the various pieces of any large collection, and much difference in the condition of them. Some, far from being the most ancient, are greatly discoloured and brittle in appearance; others retain their colour almost in its original purity and their perfect firmness of texture, seemingly unaffected by the long lapse of time. The innumerable possible accidents to which carved ivories may have been exposed from age to age will account for this great difference, and a happy forgetfulness, perhaps owing to a contemptuous neglect at first of their value and importance, may have been the cause of the comparatively excellent state and condition of many. Laid aside in treasuries of churches and monasteries, or put away in the chests and cupboards of great houses, the memory even of their existence may have passed away for century after century. It does not appear that any good method is known by which a discoloured ivory can be bleached. All rough usage of course merely injures the piece itself, and removes the external surface. Exposure to the light keeps the original whiteness longer, and in a few instances may to some extent restore it. It need hardly be observed that any other attempt to alter the existing condition, whatever it may be, as regards the colour of an antique or mediæval ivory is to be condemned.