ON THE DURABILITY OF BUILDING STONE 



375 



determined largely by the minerals which make up the mass. 

 The more porous a rock the greater the interstitial space, 

 and the greater its capacity for absorbing water, or its ab- 

 sorptive ratio. As a rule, the more porous stone is less 

 valuable as a durable building material."^' The relation of 

 porosity to specific gravity is shown in the several classes 

 of building stone in the following table, wherein are given : 

 first, the locality ; second, the specific gravity ; third, the 

 percentage of water absorbed, or the absorptions percent- 

 age, and, lastly, the computed pounds of water absorbed by 

 a cubic foot of the stone. 



Stone. 



Granite.. 

 Granite.. 

 Granite.. 



Marble 



Marble 



Marble 



Limestone. 

 Limestone. 

 Limestone. 

 Limestone. 



Sandstone . 

 Sandstone , 

 Sandstone . 

 Sandstone . 

 Sandstone . 

 Sandstone . 

 Sandstone . 

 Sandstone . 

 Sandstone . 



LOCALITY. 



Grindstone Island, Jefferson Co.. 



Ausable Forks, Essex Co 



Hallowell, Maine 



Tuckahoe, Westchester Co 



Glens Falls, Warren Co 



Gouverneur, St. Lawrence Co. . . . 



Sandy Hill, Warren Co 



Onondaga Reserv., Onondaga Co 



Chaumont, Jefferson Co 



Prospect, Oneida Co , 



Potsdam, St. Lawrence Co 



Oxford, Chenango Co 



Maiden, Ulster Co 



Albion, Orleans Co 



Warsaw, Livingston Co , . . 



East Longmeadow (Kibbe), Mass. . 



Portland, Conn 



Portland, Conn, (coarse-grained). . 



East Longmeadow (Worcester) 



Caen limestone 



Specific 



gravity. 



2 



.714 



2 



•755 



2 



■655 



2 



.868 



2 



.718 



2 



.756 



2 



.764 



2 



.708 



2 



•715 



2 



.725 



2 



.604 



2 



.711 



2 



751 



2 



599 



2 



681 



2 



480 



2 



622 



2 



635 



2 



490 



I 



839 



Percentage 

 of water 

 absorbed. 



1-55 

 0.066 



0-34 

 0.41 



o. 14 

 0.08 

 o. 16 



o. 14 

 o. 14 



0.07 



0. 14 



2.08 



1 . II 



0.82 



2.37 



2.96 



4-33 

 3-07 

 2.60 



5.48 

 16.05 



Pounds of 

 water ab- 

 sorbed per 

 cubic foot. 



2.62 

 O.Ii 

 o. 56 



0.68 

 0.25 



o. 14 



0.27 



0.24 

 0.24 

 O. 12 



o. 24 



3-37 

 1.87 

 1 .40 



3.84 



4-95 

 6.69 

 5 .02 



4.27 

 8.51 



In this table we note that the granites range in specific 

 gravity from 2.65 to 2.71; the marbles 2.70 to 2.86; the 



* " Other things being equal, it may probably be said that the value of a stone for 



building purposes is inversely as its porosity or absorbing power." — T. S. Hunt, 



Chemical and Geological Essays. Boston, Mass., 1875, p. 164. 

 24 



