138 
IOWA ACADEMY OF SCIENCE 
TABLE II. 
DETERMINATIONS IN PLATINUM GOOCH. 
Number 
Weight 
of 
Oxalate 
Calcu- 
lated 
Weight 
Error 
Weight 
of Car- 
bonate 
"Weight 
of 
Oxide 
Calcu- 
lated 
Weight 
Error 
8 
0.3912 g 
0.3911 g 
+ .0001 g 
0.3056 g 
0.1710 g 
0.1711 g 
—.0001 g 
9 - _ 
0.3945 g 
.3938 g 
+ .0007 g 
.3076 g 
.1722 g 
.1722 g 
.0000 
_ 
.3916 g 
.3913 g 
+ .0003 g 
.3058 g 
.1716 g 
.1713 g 
+ .0003 
11 
.8666 g 
.8666 g 
.0000 g 
.6770 g 
.3794 g 
.3791 g 
+ .0003 
12 
.8820 g 
.8819 g 
+ .0001 g 
.6890 g 
.3858 g 
.3858 g 
.0000 
Note. — Calculated weights based on weights of carbonates. 
The results of these experiments may be briefly summarized as follows : 
Calcium can be determined and accurately weighed as the oxalate. 
It can be very conveniently converted into the carbonate and weighed 
as such. 
The determinations can be carried out in porcelain crucibles without 
appreciable error. 
Either of the above mentioned methods is fully as accurate as the 
determination of calcium as the oxide and is much more convenient and 
rapid. 
Of the two methods^ the determination as carbonate is somewhat su- 
perior to the determination as oxalate, because of the hydroscopic nature 
of the latter substance. 
I wish at this time to express my thanks to Professor W. S. Hendrix- 
son for his suggestions and help in the working up of this series of 
experiments. 
