IOWA ACADEMY OP SCIENCE 
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under (a) is equally satisfactory with that under (b). Treatment 
(a) requires much less time and labor than (b) . 
An analysis of this layer of rock resulted as follows : 
CaCO s 
MgCO 
Si0 2 . 
AI2O3 
Fe 2 0 3 
53.62% 
44.96% 
0.83% 
0.25% 
0.34% 
100 . 00 % 
The rock is essentially a true dolomite. 
2. Silica in the Bedford Limestone. 
The specimen was obtained from a quarry near Bedford, Indi- 
ana. It is a light-colored rock, fine-grained in texture, and it is 
widely used and favorably regarded as a building material. It is 
subcarboniferous limestone. The fine powder was treated as de- 
scribed under (a) and (b) in the foregoing. The following results 
were obtained: (a) 0.54%; (b) 0.55%. The same results could 
be obtained whether one gram, three grams, or ten grams were 
used. The residue in the crucible after treatment with sulphuric 
and hydrofluoric acids was .13%. This was found to be: 
Aluminum and Iron Sulphate ..0.08 % 
Calcium Sulphate 0.058% 
0.138% 
To compare these results with those from an alkaline fusion. A 
gram of the fine powder was thoroughly mixed with seven grams 
of purified sodium carbonate, and fused in the usual way. The 
insoluble residue was found to be .53%. On treating this with 
sulphuric and hydrofluoric acids, the residue in the crucible 
amounted to 0.16%. Nothing seemed to be gained by this method. 
The first filtrates from the silica were frequently evaporated a 
second time, but no trace of residue was found. 
The analysis of the Bedford limestone resulted as follows : 
CaC0 3 93.55% 
MgC0 3 5.42% 
Fe 2 0 3 and A1 2 0 3 0.50% 
Insoluble residue mainly Si0 2 0.55% 
100.02% 
The concordant results obtained by methods (a) and (b) show 
that the silica is of the insoluble kind. 
