28 NEW YORK STATE MUSEUM 



The limestones, up to the point where calcination begins (6oo°- 

 8oo°C.) were little injured, but above that point they failed badly, 

 owing to the crumbling caused by the flaking of the quicklime. 

 The purer the stone, the more will it crumble [compare pi. 24, 

 Palatine Bridge, with pi. 22, Sandy Hill, or pi. 23, Little Falls], 

 The marble behaves similarly to the limestone; but, because of the 

 coarseness of the texture, also cracks considerably. As has been 

 mentioned before, both the limestones and marble on sudden 

 cooling seem to flake off less than on slow cooling. 



The flame tests can not be considered as indicative of the probable 

 effect of a conflagration upon the general body of the stone in a build- 

 ing, but rather as an indication of the effect upon projecting cor- 

 nices, lintels, pillars, carving and all thin edges of stonework. All 

 the stones were damaged to some extent. The samples from 

 Keeseville [pi. 13] and Northville [pi. 17] stood up very well; the 

 limestones were, as a whole, comparatively little injured, while the 

 marble was badly damaged. The tendency seems to be for the 

 stone to split off in shells around the point where the greatest heat 

 strikes the stone. The temperature of the flame probably did not 

 exceed 7oo°C., so it is safe to say that in a conflagration all carved 

 stone and thin edges would suffer. However, outside of the intense 

 heat, the limestones would act best, while the other stones would 

 be affected in the order: sandstone, granite, gneiss and marble. 



After having been heated to 85o°C., most of the stones, as 

 observed by Buckley^ emit a characteristic ring when struck with 

 metal and when scratched emit a sound similar to that of a soft 

 burned brick. It will be noted that in those stones in which iron 

 is present in a ferrous condition the color was changed to a brownish 

 tinge owing to the change of the iron to a ferric state. If the 

 temperature does not exceed 550^0., all the stones will stand up 

 very well, but at the temperature which is probable in a confla- 

 gration, in a general way, the finer grained and more compact the 

 stone and the simpler in mineralogic composition the better will it 

 resist the effect of the extreme heat. The order, then, of the refrac- 

 toriness of the New York stones which were tested might be placed 

 as sandstone, fine grained granite, limestone, coarse grained granite, 

 gneiss and marble. 



1 Mo. Bur. Geol. and Mines. Ser. 2. 1004, 2 :so. 



