imbedded in the mass. The native crystallized lime, known as Iceland or felspar, is very similar in its chemical constituents to the nearly pure carbonates which are known as statuary marble.”
In this we see the varied origin of marbles, and are able to read in their polished surfaces some of the details of the development and the causes that have resulted in the markings and veinings that make marble the most decorative of all building stones.
The physical properties of marble, as set forth by Dale in his work, “The Commercial Marbles of Western Vermont,” are stated as follows:
Marble, besides possessing the qualities of hardness, cohesiveness, compressive strength, porosity, expansiveness under heat, thermal conductivity, sonorousness, translucence and flexibility, is polishable and can be deformed in confinement under powerful compression. Its color, texture, specific gravity, hardness and porosity will be considered under other heads.
Tests made at the Watertown Arsenal give the white dolomite marble of Lee, Mass., an ultimate compressive strength of 18,047 lb. to the square inch; the calcite marbles of West Rutland and Proctor a compressive strength of 11,525 to 14,397 lb. to the square inch, and the coarse calcite marbles of South Dorset an ultimate compressive strength averaging 11,300 lb. when placed on bed and 9100 lb. when placed on edge.
Tests of the dolomite marble of Lee give it a shearing strength of 2052 lb. to the square inch and a maximum fiber strength of 1585 lb. to the square inch.
Vogt gives the compressive strength of a Norwegian dolomite marble as 24,891 lb. to the square inch, of Carrara marble as 6329 lb. and of Tyrolese statuary marble (Laas) as 16,036 lb.
Geikie in an interesting petrographic study of Edinburgh gravestones describes some slabs of white marble, presumably from Italy, firmly set into sandstone monuments, which in consequence either of their porousness and the freezing of interstitial water or else of their greater expansiveness than sandstone, or from both causes, had bulged out 2in. from their original vertical position and showed a series of rents along the crest of the bulge.
The Watertown Arsenal tests referred to above give the coefficient of expansion of dolomite marble from Lee as only 0.00000562 under a difference of temperature of 156° F. Bartlett found the expansion of marble to be 0.000005668 in. to the foot for each degree Fahrenheit.
Yamagawa determined the thermal conductivity of marble as averaging 0.00728 centimeter a second. A previous determination by Depretz was 0.0077 centimeter.
Thin slabs of ordinary Carrara marble have a marked sonorousness when struck with a hammer. The Vermont calcite marbles are only feebly sonorous, but on the other hand the dolomite marbles of Lake Champlain possess more sonorousness than the Carrara marble.
White marbles become transparent or nearly so in thin sections prepared for the microscope, but differ considerably in translucence on the rough or polished face. Some have a waxy look, which is probably attributable to the greater transparence of their grains; others are milk-white and opaque. Lepsius in connection with his study of Greek marbles determined that the best Pentelicon marble admits light to a depth of 0.59 in., and the Parian to 1.37 in. Upon this feature largely rested the reputation of Parian marble. Lindenmann gives the translucence of Carrara statuary marble as from 1.18 to 1.57 in. The coarse calcite marble formerly quarried at Adams, Mass., is unusually translucent.
The flexibility of marble has long been known. It probably depends largely on the shape and cohesion of its grains.
The important experiments of Adams, Nicholson and Coker show that marble when tightly inclosed can be deformed—that is, it flows. They fitted cylinders of Carrara and Vermont marble tightly into steel tubes and applied great pressure to the ends of the cylinders, which caused them to bulge out on the sides, distending the inclosing tube. When the deformed marble was sliced and examined microscopically it was found to be solid, but many molecular changes had taken place in the individual crystalline plates, such as slippage and twinning. They also found that the marble if deformed at ordinary temperature was stronger under slow than under rapid deforma
MARBLE DETAILS, McKINLEY BIRTHPLACE MEMORIAL,
NILES, OHIO
McKIM, MEAD & WHITE, ARCHITECTS
In this we see the varied origin of marbles, and are able to read in their polished surfaces some of the details of the development and the causes that have resulted in the markings and veinings that make marble the most decorative of all building stones.
The physical properties of marble, as set forth by Dale in his work, “The Commercial Marbles of Western Vermont,” are stated as follows:
Marble, besides possessing the qualities of hardness, cohesiveness, compressive strength, porosity, expansiveness under heat, thermal conductivity, sonorousness, translucence and flexibility, is polishable and can be deformed in confinement under powerful compression. Its color, texture, specific gravity, hardness and porosity will be considered under other heads.
Tests made at the Watertown Arsenal give the white dolomite marble of Lee, Mass., an ultimate compressive strength of 18,047 lb. to the square inch; the calcite marbles of West Rutland and Proctor a compressive strength of 11,525 to 14,397 lb. to the square inch, and the coarse calcite marbles of South Dorset an ultimate compressive strength averaging 11,300 lb. when placed on bed and 9100 lb. when placed on edge.
Tests of the dolomite marble of Lee give it a shearing strength of 2052 lb. to the square inch and a maximum fiber strength of 1585 lb. to the square inch.
Vogt gives the compressive strength of a Norwegian dolomite marble as 24,891 lb. to the square inch, of Carrara marble as 6329 lb. and of Tyrolese statuary marble (Laas) as 16,036 lb.
Geikie in an interesting petrographic study of Edinburgh gravestones describes some slabs of white marble, presumably from Italy, firmly set into sandstone monuments, which in consequence either of their porousness and the freezing of interstitial water or else of their greater expansiveness than sandstone, or from both causes, had bulged out 2in. from their original vertical position and showed a series of rents along the crest of the bulge.
The Watertown Arsenal tests referred to above give the coefficient of expansion of dolomite marble from Lee as only 0.00000562 under a difference of temperature of 156° F. Bartlett found the expansion of marble to be 0.000005668 in. to the foot for each degree Fahrenheit.
Yamagawa determined the thermal conductivity of marble as averaging 0.00728 centimeter a second. A previous determination by Depretz was 0.0077 centimeter.
Thin slabs of ordinary Carrara marble have a marked sonorousness when struck with a hammer. The Vermont calcite marbles are only feebly sonorous, but on the other hand the dolomite marbles of Lake Champlain possess more sonorousness than the Carrara marble.
White marbles become transparent or nearly so in thin sections prepared for the microscope, but differ considerably in translucence on the rough or polished face. Some have a waxy look, which is probably attributable to the greater transparence of their grains; others are milk-white and opaque. Lepsius in connection with his study of Greek marbles determined that the best Pentelicon marble admits light to a depth of 0.59 in., and the Parian to 1.37 in. Upon this feature largely rested the reputation of Parian marble. Lindenmann gives the translucence of Carrara statuary marble as from 1.18 to 1.57 in. The coarse calcite marble formerly quarried at Adams, Mass., is unusually translucent.
The flexibility of marble has long been known. It probably depends largely on the shape and cohesion of its grains.
The important experiments of Adams, Nicholson and Coker show that marble when tightly inclosed can be deformed—that is, it flows. They fitted cylinders of Carrara and Vermont marble tightly into steel tubes and applied great pressure to the ends of the cylinders, which caused them to bulge out on the sides, distending the inclosing tube. When the deformed marble was sliced and examined microscopically it was found to be solid, but many molecular changes had taken place in the individual crystalline plates, such as slippage and twinning. They also found that the marble if deformed at ordinary temperature was stronger under slow than under rapid deforma
MARBLE DETAILS, McKINLEY BIRTHPLACE MEMORIAL,
NILES, OHIO
McKIM, MEAD & WHITE, ARCHITECTS