104 IOWA ACADEMY OF SCIENCES. 



SOME RECENT ANALYSES OF IOWA BUILDING 

 STONES; ALSO OF POTABLE WATERS. 



NICHOLAS KNIGHT. 



A. Building Stones— 



The rocks herein described were analyzed in the chem- 

 ical laboratory of Cornell College, under the direction of 

 Dr. N, Knight. The composition of the rocks varies from 

 nearly tyj^ical dolomite to admixtures in different propor- 

 tions of calcium carbonate and dolomite. 



1, This is a bluish drab saccharoidal rock, situated near 

 the base of the Iowa Devonian series, at Rochester, Iowa. 

 It is of special interest because locally believed to contain 

 silver. A miner's shaft twenty-two feet deep has been 

 sunk to it, and several analyses are said to have been 

 made, showing a large amount of silver. Professor W. H. 

 Norton, of the Iowa Geological Survey, was unable to 

 authenticate any of the analyses. He found no geological 

 grounds for the slightest suspicion of any precious metal 

 in these beds. This analysis was made, not to disprove 

 the presence of silver, but to show the lithological change 

 from the subjacent dolomites of the Silurian. The speci- 

 men was analyzed by Miss Minerva Herrinton, A. B. 



CaCOo 78.75 percent. 



MgCUs 20.16 per cent. 



Ff.;03 and AhOa O.iO 



8ic2 0.4 percent 



MnO_... 0.2 percent. 



Total yy.G i per cent. 



The rock varies widely from a true dolomite, which con- 

 tains 



CaCOa 54.35 



MgCOi 45.65 



