TESTS OF WISCONSIN BUILDING STONE 543 



such extreme conditions, in an ordinary atmosphere it would be 

 many years before the gas would have any appreciable effect 

 upon the limestone in the walls of a building. 



EFFECT OF CARBONIC ACID GAS - 



Eleven samples of limestone and dolomite were tested to 

 determine the effects of carbonic acid gas in a moist atmosphere. 

 After treatment for forty-four days there was apparently no 

 deterioration either in weight or color. 



EFFECT OF HIGH TEMPERATURE 



Few experiments have thus far been performed to determine 

 the limit of temperature which different kinds of stone will stand 

 without injury. 1 It is known, however, that a stone will stand a 

 much higher temperature when heated and cooled slowly than 

 when heated and cooled rapidly. 



Samples of granite from six different quarries were tested in 

 a muffle furnace to determine the temperature which they would 

 stand without being destroyed. The samples were all practically 

 uninjured up to a temperature of 1200 F. but most of them were 

 destroyed before a temperature of I 500 F. was reached. Eleven 

 different samples of limestone from as many different quarries 

 were tested and each of them was partially calcined before a 

 temperature of 1400 F. was reached. The eleven samples of 

 sandstone which were tested were mostly destroyed at a temper- 

 ature of less than 1200 F. although in one instance a temper- 

 ature of 1500 F. apparently left the sample uninjured. 



All the heated samples when struck with a hammer or 

 scratched with a nail emitted a sound very similar to that given 

 off by brick. Planes of lamination were brought out more dis- 

 tinctly as the temperature increased. 



The samples of granite cracked differently depending upon 

 whether they were coarse or fine grained. The very coarse 

 grained granite samples broke in a great many places and may 

 be said to have exploded. The cracks were so numerous in one 



1 See "Notes on Building Stones " by Hiram Cutting, Montpelier, Vt., 1880. 



