PART XI. SANDSTONE GROUP OF BUILDING STONES. CHAPTER I. SILICEOUS FKEESTONES. Sandstein (Germ.) Gres (Fr.) Sandstone, sometimes called ‘ freestone,’ is very largely employed as a building material in some portions of the British Isles, especially the northern ; and it possesses this advantage over limestones and dolomites, that it is better able to resist the chemical action of the smoky atmosphere of large towns. Some varieties, however, are, on the other hand, equally liable to the influence of atmospheric dis integration, depending very much on the nature of the cementing matter; and quite as much judgment is necessary in the selection at the quarry of a good and durable sandstone, as of any other kind of building material. Of the injurious effects produced by simple weathering on sandstones of inferior quality, the venerable cathedral and churches of Chester,