Potash, the type of all the alkalies, has of late years been rather scarce, and soda has, in a great measure, supplanted it, because soda is always obtainable from co'mmon salt, of which there is plenty both in the land and sea. But there are many processes where alkali is required, for which potash alone will do, as for instance, in the preparation and coloring of many fabrics ; therefore it is with pleasure that we announce the discovery of a German chemist. Dr. Meyer, that the vast amount of the necessary alkali for ages locked up in the mineral, feldspar, can be made available. His method is, to calcine 100 parts of feldspar with from 140 to 180 parts of lime, either as hydrate or chalk ; these are made into balls, and calcined in a suitable furnace, and afterwards the mass is powdered and heated in water at a pressure from 6 to 8 atmospheres. The potash can then be easily extracted, having been brought into a state in which it can be cheaply worked ; and the crude mixture, with the addition of a little clay, furnishes an excellent hydraulic cement.