FIRE TESTS OF NEW YORK BUILDING STONES 7 



Limestones and marble stand close up to and in some instances 

 exceed the value of freestones. 



The conglomerates and slates show no capacity to standing 

 heat, as the slates crack and conglomerates are almost immediately 

 ruined. 



With regard to the granites, Cutting^ further states: 



All these samples of building stones have stood heat without 

 damage up to 5oo°C.^ At 600° a few are injured, but the injury 

 in many cases commences at or near that point. When cooled 

 without immersion, they appear to the eye to be injured less 

 but are ready to crumble and I think they are many times nearly 

 as much impaired, and always somewhat injured, where water 

 produces any serious injury. 



As to the sandstones, he continues: 



While as a whole they stand both heat and water better than 

 granite, they are more or less injured. In fine, the capability of 

 resisting heat has little connection with their density. 



Of limestones, he says: 



Limestones and marbles have come through the fiery ordeal 

 more favorably than any of the other stones . . . The lime- 

 stones and marbles seldom crack from heat and water. But 

 when heat from the outside is excessive, they slightly crumble 

 on the outside if water is thrown on them. When they are cooled 

 without the application of water, the injury is much less. 



The specimens tested stood fire well, as a whole, up to the tem- 

 perature of heat necessary to convert them into quicklime, and 

 at such a heat, if long continued, they are changed so as to flake 

 off and crumble down. In most cases this heat is greater than 

 9oo°F. and in some cases beyond iooo°F. 



N. H. WinchelP has carried on a series of experiments on the 

 building stones of Minnesota. He made use of a muffle furnace 

 in which the temperature was raised to a red heat. One and 

 one half to two inch cubes were placed in the furnace, and during 

 heating were removed once or twice so that the effects of the 

 treatment might be observed. The samples were then removed 

 from the furnace and while hot were immersed in a tank of water 

 and the results again noted. A study of the tables of that report 

 shows that most of the stones cracked more or less. The effect 

 of the sudden cooling of the stone was more disastrous than the 

 mere heating. 



Buckley^ in his experiments on the building stones of Wisconsin 

 used I and 2 inch cubes in a muffle furnace in which the 

 temperature was gradually increased from 600° to 1500° F. The 

 effect of heating was noted from time to time. At 1300° to 1500° 



^ Idem. 1880. 22:257, 287, 304. 



2 The author here refers to the centigrade scale. 



3,Minn. Geol. & Nat. Hist. Bur. Final Rep't. 1884. 1:186. 



4 Wis. Geol. & Nat. Hist. Sur. Bui. 1808. 4:73- 



