26 NEW YORK STATE MUSEUM 



SUMMARY 



From the details above given some generalizations can be drawn 

 which are of interest and of value. It is difficult, however, to group 

 the different kinds of stone in any order, for they vary among them- 

 selves and also act differently under different conditions. A stone 

 which imder some conditions stands up very well, will disintegrate 

 under other conditions. Thus, for example, the granite from North- 

 ville [pi. 17] acted very badly on fast cooling after having been 

 heated to 850°, yet, under the combined action of the flame and 

 water, it was little damaged. Additional variations of this char- 

 acter are brought out by a close study of the tables of fire tests, all 

 of which goes to show that, for one temperature, the order of resist- 

 ance will differ from the order given for another temperature. 



At 55o°C. (102 2°F.) most of the stones stood up very well. The 

 temperature does not seem to have been high enough to cause much 

 rupturing of the samples, either upon slow or fast cooling. The 

 sandstones, limestones, marble and gneiss were slightly injured, 

 while the granites seem to have suffered the least. 



The temperature of a severe conflagration would probably be 

 higher than 55o°C. but there would be buildings outside of the direct 

 action of the fire which might not be subjected to this degree of 

 heat and in this zone the stones would suffer little injury. The 

 sandstones might crack somewhat; but, as the cracking seems to 

 be almost entirely along the bed, the stability of the structure 

 would not be endangered, provided the stone had been properly 

 set. 



The gneiss would fail badly, especially if it were coarse grained 

 and much banded. The coarse grained granites might suffer to 

 some extent. .These, though cracked to a less extent than the 

 sandstones, would suffer more damage and possibly disintegrate 

 if the heat were long continued because the irregular cracks, in- 

 tensified by the crushing and shearing forces on the stone incident 

 to its position in the structure, would tend to break it down. The 

 limestones and marble would be little injured. 



The temperature of 85o°C. (i562°F.) represents fairly the probable 

 degree of heat reached in a conflagration, though imdoubtedly 

 it exceeds that in some cases. At this temperature we find that the 

 stones behave somewhat differently than at the lower temperature. 

 All the cubes tested were injured to some degree, but among them- 

 selves they vary widely in the extent of the damage. 



All the igneous stones and the gneiss at 85o°C. suffered injury in 

 varying degrees and in various ways. The coarse grained granites 



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