DIASTASE. A peculiar substance generated during the germination of bar ley, wheat, &c., which tends to accelerate the formation of sugar during the fer mentation of worth. It is precipitated from infusions of bruised malt by alcohol. It is the principle which, by its reaction on starch, tends to develop sugar in the processes of germination and malting.
DIE. in coinage, is the instrument by which the impressions are given upon the various denominations of coin. The fol lowing is an outline of the die manufac ture: The engraver selects a forged plug of the best cast steel of proper dimen sions for his intended work, and having carefully annealed it, and turned its sur faces smooth in the lathe, proceeds to en grave upon it the intended device for the coin. 'When this is perfect, the letters are put in, and the circularity and size duly adjusted; it is then hardened, and is termed a matrix. Another plug of soft steel is now selected, and the matrix be ing carefully adjusted upon it, they are placed under a very powerful fiy-press, and two or three blows so directed as to commence an impression of the matrix upon the plug ; this is then annealed, and the operation repeated till the plug re ceives a perfect impression of the work upon the matrix. This impression is of
course in relief, the original work upon the matrix being indented, and produces what is termed the punch. This being duly shaped in the lathe, is hardened, and is employed in the production of impres sions in soft steel or dim,. which, being properly turned and are exact jae-.simtles of the original matrix, and are used in the process of coinage. When a pair of dies are made of good steel duly hardened and tempered, and are carefully used, they will sometimes yield from two to three hundred thousand impressions before they become so far worn or injured as to require to be removed from the coiling presses.