In Europe, as far as I know, wax has been everywhere used for sealing since the earliest ages. Writers on diplomatics, however, are not agreed whether yellow or white wax was first employed; but it appears that the former, on account of its low price, must have been first and principally used, at least by private persons. It is probable also, that the seals of diplomas were more durable when they consisted of yellow wax; for it is certain that white wax is rendered more brittle and much less durable by the process of bleaching. Many seals also may at present be considered white which were at first yellow; for not only does wax highly bleached resume in time a dirty yellow colour, but yellow wax also in the course of years loses so much of its colour as to become almost like white wax. This perhaps may account for the oldest seals appearing to be of white, and the more modern of yellow wax. These however are conjectures which I submit with deference to the determination of those versed in diplomatics. In the course of time wax was coloured red; and a good deal later, at least in Germany, but not before the fourteenth century, it was coloured green, and sometimes black. I find it remarked that blue wax never appears on diplomas; and I may indeed say it is impossible it should appear, for the art of giving a blue colour to wax has never yet been discovered; and in old books, such as that of Wecker, we find no receipt for that purpose. Later authors have pretended to give directions how to communicate that colour to wax, but they are altogether false; for vegetable dyes when united with wax become greenish, so that the wax almost resembles the hip-stone; and earthy colours do not combine with it, but in melting fall again to the bottom. A seal of blue wax, not coloured blue merely on the outer surface, would be as great a rarity in the arts as in diplomatics, and would afford matter of speculation for our chemists; but I can give them no hopes that such a thing can ever be produced[357]. The emperor Charles V. in the year 1524 granted to Dr. Stockamar of Nuremberg, the privilege of using blue wax in seals;--a favour like that conferred in 1704 on the manufactories in the principality of Halberstadt and the county of Reinstein, to make indigo from minerals. It was certainly as difficult for the doctor to find blue wax for seals as for the proprietors of these manufactories to discover indigo in the earth[358].