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 typical 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. 
CaCO 78.75 per cent 
MgCOs 20.16 per cent. 
FesOa and ALOs 0.10 
Sic 2 0.4 percent 
MnO _ ... 0.2 per cent. 
Total 09.61 per cent. 
The rock varies widely from a true dolomite, which con- 
tains 
CaCOs 
MgCO 
54.35 
45.65 
