Page:A Practical Treatise on Brewing (4th ed.).djvu/226

210 with malt, which, in a manner not yet known, by a substance contained in it (diastase), has the power of lacerating the cuticles of the starch granules. The diastase contained in malt is said to be a solid, white, tasteless, uncrystallised body, soluble in water, but insoluble in alcohol. Dissolved in water, it turns sour very soon. Its most remarkable property is, that one part of it is sufficient to tear, or burst open, 2000 parts of potatoe starch diluted by 8000 parts of water, by which means its dextrin becomes free, and its insoluble cuticles are either precipitated or made to swim on the surface. Diastase is produced by diluting malt-meal, or bruised malt, in cold water, filtering the fluid, and heating it: it becomes turbid, and some substance resembling white of eggs is precipitated: strain again, and add absolute alcohol (free of water), whereby the diastase falls to the bottom, while the sugar which was in the malt remains dissolved. It is then dried by a low heat, because a higher one would decompose it. The heating of the solution is not necessary: or the diastase may be separated by the mere action of alcohol. Diastase, produced in the above manner, is not quite pure, still containing some azotic substance, which may be removed by a repeated digestion of the product by water, and precipitation by alcohol. In seeds, which have undergone germination, it is contained in the immediate neighbourhood of the blade, but not in the