194 Henry C. Richards: 



magnesia. The presence of this material is detrimental, as it is 

 readily removed under ordinary weathering conditions, thus 

 weakening the stone. 



The Barley has much the same composition as the Bacchus 

 Marsh stone, but has less argillaceous material, and consider- 

 ably more carbonates, the 1.82 per cent, of carbon dioxide is 

 high, and occurring in a stone of weak physical features like 

 this one is alone sufficient to condemn it for city structures. 

 Manganous oxide occurs to the extent of .20 per cent., and in the 

 form of manganese carbonate appears as the pink staining which 

 the stone shows irregularly through it. 



The Egertoth and Gretndale stones are similar to one another 

 in composition, and are fairly high in silica. They contain a 

 fair amount of argillaceous material, but there is nothing in 

 either of the stones which is liable to chemical removal or 

 alteration to any extent under normal weathering conditions. 



Table of (Jiiemical Analyses. 



Total - 99.73 99.52 100.22 99.63 99.75 99.53 100.52 '.»S).54 



