| J.D. Dana - 1855 - 440 Seiten
...fine grained argillaceous variety, commonly of a dark dull blue or bluish-black color, or somewhat purplish. To be a good material for roofing, it should...in water, It should also be pure from pyrites and every thing that can undergo decomposition on exposure. In the United States, a good material is obtained... | |
| Tennessee. Geological Survey, James Merrill Safford - 1856 - 178 Seiten
...for roofing is generally of a dark-bluish or purplish color. The color is not, however, important. " To be a good material for roofing, it should split...immersion for a while in water. It should also be free from pyrites, and every thing that can undergo decomposition on exposure."* 273. 4th. Flagging-Stones.—When... | |
| James Dwight Dana - 1859 - 236 Seiten
...fine grained argillaceous variety, commonly of a dark dull blue or bluish-black colour, or somewhat purplish, To be a good material for roofing, it should...in water. It should also be pure from pyrites and everything that can undergo decomposition on exposure. Roofing slates occur in England, in Cornwall,... | |
| James Merrill Safford - 1869 - 604 Seiten
...for roofing is generally of a dark-bluish or purplish color. The color is not, however, important. "To be a good material for roofing, it should split...immersion for a while in water. It should also be free from pyrites, and every thing that can undergo decomposition on exposure."* FLAGSTONES. (17.)... | |
| James Merrill Safford - 1869 - 604 Seiten
...for roofing is generally of a dark-bluish or purplish color. The color is not, however, important. "To be a good material for roofing, it should split...immersion for a while in water. It should also be free from pyrites, and every thing that can undergo decomposition on exposure.''* FLAGSTONES. (17.)... | |
| James Merrill Safford - 1869 - 598 Seiten
...roofing is generally pf, a dark-bluish or purplish color. The color is not, however, important. u Tp.be a good material for roofing, it should split easily...may be tested by weighing, after .immersion; for a wjnle in wa,t@r. It should also be free from pyrites, and every thing that can undergo decomposition... | |
| Junius Brutus Wheeler - 1876 - 504 Seiten
...is a .stratified rock of great hardness and density, commonly of a dark dull bine or purplish color. To be a good material for roofing, it should split...slates, and admit of being pierced for nails without being fractured. It should be free from everything that can on exposure undergo decomposition. The... | |
| Junius Brutus Wheeler - 1876 - 502 Seiten
...is a stratified rock of great hardness and density, commonly of a dark dull blue or purplish color. To be a good material for roofing, it should split...slates, and admit of being pierced for nails without being fractured. It should be free from everything that can on exposure undergo decomposition. The... | |
| Junius Brutus Wheeler - 1876 - 504 Seiten
...is a stratified rock of great hardness and density, commonly of a dark dull blue or purplish color. To be a good material for roofing, it should split...slates, and admit of being pierced for nails without being fractured. It should be free from everything that can on exposure undergo decomposition. The... | |
| Junius Brutus Wheeler - 1876 - 506 Seiten
...is a stratified rock of great hardness and density, commonly of a dark dull blue or purplish color. To be a good material for roofing, it should split...slates, and admit of being pierced for nails without being fractured. It should be free from everything that can on exposure undergo decomposition. The... | |
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