BUILDING AND ORNAMENTAL STONES OF N.S.W. 



193 



Effect of Heat on New South Wales Building Stones — cor 



Rock Treated. 



Temp, of 



Furnace 



°C. 



Time in 

 Furnace 

 Minutes 



767 



20 



806 



15 



806 



15 



830 



15 



784 



45 



783 



35 



544 



20 



701 



30 



How Treated and Remarks. 



Bowral 

 Trachyte 



Moruya 

 Granite 



)> >) 



Barren Jack 

 Granite 



JJ 55 



Gabo Island 

 Granite 



5) 5) 



Tenterfield 

 Granite 



Semi-submerged in cold water ; 

 afterwards cooled off beneath 

 tap. Badly cracked along edge 

 on portion submerged, colour 

 changed to deep brown. 



Seven minutes after entry into 

 furnace badly cracked in 

 several places. On removal 

 quite shattered into small 

 fragments 



Ten minutes after entry into 

 furnace this specimen showed 

 number of small cracks. On 

 removal plunged into cold 

 water, immediately flew to 

 pieces with report. 



After 3 minutes cracked across 

 diagonally. Removed after 15 

 minutes and allowed to cool 

 slowly; cracked in several 

 places but not shattered, other- 

 wise stood the test well. 



Allowed to heat gradually in 

 furnace, taken out unaltered 

 and plunged into cold water, 

 several prominent cracks at 

 once appeared, otherwise stood 

 the test well. 



The cube was placed in cold 

 furnace and heated gradually. 

 At 7 1 7°a small crack appeared. 

 After removal, cube very badly 

 cracked in many places — 

 almost shattered. 



Heated gradually and plunged 

 suddenly into cold water. 

 Almost unaffected, several 

 small cracks can be seen on 

 close examination. 



Heated gradually, at 701° it was 

 noticed that the cube was 

 cracked and on removal it 

 crumbled into fragments. 



