130 
IOWA ACADEMY OF SCIENCES. 
2 
3 
4 
Mg 
Mg 
Mg 
0 = 0.59% 
O = 0.47% 
O = 0.75% 
► An average of 0.63 per cent. 
Ill . Determinations by C. A. TJtt. 
1. The analysis of the specimen gave: 
PER CENT. 
Ca C0 3 52.92 
Mg C0 3 37.56 
Mg O = 0.47 = Mg C0 3 1.84 
Fe 3 0 3 and Al 2 0 3 6.26 
Si O s 1.44 
100 02 
2 Mg O = 0.96 per cent. 
3 Mg 0 = 0.15 percent. 
4 Mg 0 = 1.28 p ercent - 
5 Mg O = 0.47 percent. 
6 Mg O = 0.228 per cent. 
In 1, 2 and 4 of this series after dissolving the calcium 
and magnesium oxalates with hydrochloric acid and pre- 
cipitating with ammonia the calcium precipitate was at 
once filtered. It is therefore evident that the calcium was 
not all precipitated, and afterwards came down and was 
determined as magnesium. This easily accounts for the 
large amounts obtained in these determinations. 
Next such a mixture of pure Iceland spar and dolomite 
was taken that the calcium carbonate largely predominated. 
The analysis of the mixture is given below. 
PER CENT. 
CaCO s 87.035 
MgCOg.. 10.828 
MgO = 0.47 = MgCO s 0.990 
SiO*.. 0.06 
Fe 2 Os and A1 2 0 3 1 08 
99.993 
2. Mg O = 0.15 per cent. 
Instead of a gram but 0.2033 gram, not of the mixture but of 
the original substance was used. The small quantity Mg 0 
was 0.66 per cent. From the foregoing it appears that it 
makes no difference if the percentage of magnesium is 
relatively small, or if a small amount of substance is used. 
About the same quantity of magnesium falls down with 
the calcium. 
