The place in which the king's money is coined. Formerly mints existed in almost every country, for notwithstanding the coining of money appears at all times to have been considered a special prerogative of the crown, the Saxon princes ceded the privilege to their subjects to a great extent, reserving at the same time eight mints for the City of London. This arrangement was continued by the Norman kings with little alteration until the period of Richard I., who procured from the east of Germany, persons well skilled in the art, for the purpose of improving the coinage. From this time to the accession of Edward II. a. d. 1307, but small progress appears to have been made. That prince however endeavoured by introducing many alterations in the constitution of the mint, to improve the coinage. From this period a considerable time appears to have elapsed, without any material changes taking place, until the appointment of a Committee in 1798, to consider the establishment and constitution of his Majesty's mint, the result of which was the erection of the present mint on Tower Hill, between 1805 and 1810, with highly improved machinery, and increased facilities for carrying on the process of coining extensively and advantageously.
The various chemical manipulations necessary for reducing the metal to its due degree of purity previous to coinage, it is not our province to enter into; we shall, therefore, proceed to a description of the different processes of coining, after the metal has been received in the melting house. The usual mode was to melt the silver in black lead pots, and a considerable coinage of tokens for the Bank of Ireland was produced in this manner. The importations being entirely Spanish dollars, and the tokens of the same standard, the melter could easily melt them in quantities of 60 lbs. troy, which was done. But the inconvenience of this mode was ultimately severely felt, because ingots of silver of different qualities could not be used for coinage, from the difficulty of blending several together in one pot to produce the proper standard of our money. This obstacle was so severely felt that, in 1777, Mr. Alchorne, then principal assay master, was commissioned by Government to visit the mints of Paris, Brussels, Rouen, and Lille, for the purpose of collecting information with respect to the arts of coining as practised in those mints, and more particularly the most approved mode of melting silver in large quantities-. Alchorne's intimate knowledge of the English mint, together with his great acquirements as a practical chemist, eminently fitted him for the undertaking; and his observations on the coin and coinage of France and Flanders, are alike creditable to his judgment and knowledge.
It is recorded in the documents of the mint, that at the recoinage of William III. the pots of silver weighed 400 pounds troy, and upwards, and it is somewhat extraordinary, that no trace of the process by which this was accomplished has been found; it is, therefore, mere matter of conjecture that pots of wrought iron were used.
In 1758, some trials for melting silver in wrought iron pots took place, by means of a blast furnace, but they were found so inconvenient, laborious, and profitless, as to cause the process to be abandoned. In 1787, some new experiments were tried by Mr. Morrison, (then deputy master and worker,) who conducted the meltings. A blast furnace was again tried and again abandoned. He next attempted to melt the silver in large black lead pots, containing from 100 lbs. to 120 lbs. troy; but the repeated breaking of these pots, although guarded on the outside with luting, proved a great interruption to the business, and serious loss to the melter. Trial was likewise made with cast iron pots, but these were found subject to melt, and the iron consequently got mixed with the silver. The work too was continually stopped by the king's assayer, the metal not being of the proper standard, in consequence of being refined by the process of melting, and lading it with ladles from the pot.
Great difficulties likewise were experienced in blending ingots of different qualities so as to produce the proper standard, the pots not being sufficiently large to contain the larger ingots of 60 to 80 lbs. troy, when blended together. It was therefore obvious that this mode of conducting the silver meltings was exceedingly defective, and was in consequence abandoned. Experiments were then tried with a reverberatory furnace, built after the model of those used in the Lille mint, but with no better success; and the process was, as in former rases, abandoned. The principal obstacle here appears to have been the great refinement of the silver in the melting, by the oxidation of the alloy. In 1795 and 1798 further trials were made by Mr. Morrison, for the purpose of overcoming this apparently insurmountable difficulty. In these experiments he tried three furnaces of different constructions, and although he accomplished much towards his object, there remained still a serious imperfection, arising from the process of dipping out the metal from the pots with ladles, which in addition to chilling the metal, was exceedingly laborious, and fraught with many disadvantages.
In 1803 Mr. Morrison died, without bringing the process of melting silver to that degree of perfection which, had he survived, by the activity of his intellect, great knowledge of his subject, and unwearied perseverance in its prosecution, he would, doubtless, have accomplished. His son, who succeeded to his situation, appears to have inherited his father's active and intelligent mind; for in a short period he so successfully exerted himself for the accomplishment of the object sought to be attained, that by the construction of a furnace adapted for the use of cast-iron pots, the use of pots of a size capable of melting from 400 to 500 lbs. troy at one charge, the adoption of such machinery as would supersede the clumsy and wasteful process of lading the silver from the pots when melted; and lastly, the introduction of the use of moulds made of cast iron, in place of those then used, which were made of sand, the process of melting silver, so far from being a laborious, troublesome, and expensive process, became simple, and efficient in operation, and capable with ease of melting 10,000 lbs. troy of silver daily. The illustration opposite exhibits a perspective view of the furnace at present in use. A A are the furnaces in which the metal is melted.