TESTS OF WISCONSIN BUILDING STONE 529 



dolomite, or marble in the United States. The stone which 

 gave this test was a thoroughly crystalline, well compacted, 

 and homogenous dolomite. The weakest sample tested gave a 

 crushing strength of a little over 6600 pounds per square inch. 

 The strength of the weakest limestone is very little less than 

 that of the ordinary sandstones tested. The sample which gave 

 the highest test was from the Marblehead Lime and Stone Com- 

 pany's quarry in the Niagara formation. Other samples from 

 the Niagara formation gave tests of 39,983 pounds, 36,731 

 pounds, 33,485 pounds, 32,171 pounds, and 31,800 pounds per 

 square inch. 



The crushing of the samples of limestone was ordinarily 

 accompanied with less noise than the granite. Occasionally the 

 samples scaled off along, the edges and corners before the maxi- 

 mum load was applied. In some cases two pyramids were 

 developed, but as a rule, only one remained after crushing the 

 more perfectly prepared cubes. The pyramids resulting from 

 the crushing of limestone are ordinarily much steeper and more 

 slender than those of the granite. Occasionally wedge-like 

 forms were developed which resembled the wedge-shaped 

 pyramids of the granite, as shown in Plate II, Fig. 2 and Plate 

 IV, Fig. 3. Occasionally the samples are reduced to splinters, 

 even the pyramids falling in pieces when raised from the steel 

 plate. The cone which remained after the "record sample" of 

 limestone was crushed is shown in Plate III, Fig. 6. Other 

 typical pyramids resulting from crushing limestone samples are 

 shown in Plate III, Figs. 1-5. 



The crushing strength was determined for forty-five samples 

 of sandstone from eleven different quarries. The samples from 

 several of the quarries were thoroughly indurated while others 

 were very soft and incoherent. In most cases the cementing 

 material was silica but in some of the weaker samples iron oxide 

 was the principal bonding constituent. Compared with the 

 strength of the granite and limestone, the sandstone may be 

 considered relatively weak. The sample which gave the high- 

 est strength test was from the quarry of the Chicago and 



