1869.] Cryolite. 579 annum, and being both willing and anx- ious to induce others to enter into soda and other manufactures; selling cryolite to responsible parties onty, and taking stock, in the new companies, for their profit : — as, with the duty on Cry- olite, and the low import duties on soda, there is no profit to induce others to enter into the business : — as it is im- portant to introduce the manufacture of Hot-Cast Porcelain — an American Invention — into general use, in this countiy, as also the production of Aluminium, a precious metal : — as, owing to the present method of producing most paiter " stock," or pulp, depending entirely on the facility of obtaining cheap soda, if this countiy can be under- sold in that comraodit}', we should be dependent on Europe for nearly all the paper used by the newspaper press, and much of that taken for books, a proba- ble embarrassment likely to be much increased in the event of a conflict with Great Britain : — and, finalty, as, in case of war with a maritime power, the soda manufactures of this country would, otherwise, be slow in starting; a great calamity to many interests ; and, consequently, a cause of detri- mental depression throughout the grand commonwealth, which should always be most strengthened, when most assailed. PATENT METAL ROOFING. THE kind of roofing we shall dis- cuss upon this occasion, is that of the Patent Metal Company, of No. 114 North Sixth Street, Philadelphia. We have not been furnished with the composition in this instance ; but any one, so far interested as to be specially curious, can readily be satisfied by an application to the Patent Office. The compound itself is about the color of new type-metal, or somewhere between that of polished steel and bright tin. It is not subject to rust ; and, con- sequently, does not require paint. It is suitable for roofing, water-cool- ers, refrigerators, bath-tubs, bulkheads, spouting, water-pipe, milk-cans, and cooking vessels of all kinds. The joints are made — and well made — by simpby lapping one sheet half an inch over another, and running a solder- ing-iron along over the lap, with rosin, although in roofs and linings, for greater security, they are in general regularly soldered. The hard or medallion metal, used for roofing, when thrown into the form of inch-and-a-quarter pipe, did not break, but only opened in the seam, with a pressure of 162 pounds to the square inch. Ordinary lead service- pipe, for water, usually carries about 16 pounds to the square inch. From its nature, of course, this metal- lic compound can be applied to cover any part of any building, at whatever angle, requiring effectual protection from the weather. This metal is put on a roof in large sheets, with a simple edge roll ; and unlike most metal roofs is not affected by contraction or expansion, through the severest extremes of the American climate. The Company at first experimented, in roofing, with a soft compound of the same general appearance, but darker lustre, which — after a j-ear's solicitude — they reluctantly found to be unsuit- able ; but their medallion metal has stood every test. The soft metal, however, has many important qualities of its own. It is the only known substitute for Chinese sheet lead in lining chests and other utensils, designed for retaining the strength,
