IOWA ACADEMY OF SCIENCES 
171 
If one looks for all the substances that have been found in dolomites, 
free and combined water, organic matter, alkalis S. SO3, TiOg, P2O5, 
Sro and BaO, these in addition to the silica, ferrous and ferric iron, and 
alumina, and determines all the constituents present, it would constitute 
a somewhat complicated analj^'sis, and would afford a large variety of 
practice. 
The estimation of the carbon dioxide by the Bunsen method contin- 
ues in favor in our laboratory. The amount of carbon dioxide obtained 
in the specimen of argillaceous limestone, which was the subject of the 
co-operative analysis by the two government officials w^as 30.59 per cent, 
and 30.77 per cent. One of our students obtained 30.76 per cent, before 
the results were published in the February number of the Journal of the 
American Chemical Society. 
Magnesite — ■ 
A. The calcium was precipitated according to the method of 
^Scheerer. A half gram of the powdered mineral was changed to the 
sulphate. Alcohol was added to the aqueous solution until a persistent 
cloudiness was produced. After standing some hours all the calcium 
sulphate is precipitated. If too much alcohol has been added, some of 
the magnesium sulphate will also be precipitated, in which case the two 
sulphates are dissolved in water and the calcium is precipitated with 
alcohol or with ammonium oxalate. 
B. The magnesite was dissolved in hydrochloric acid and an attempt 
was made to precipitate the calcium with ammonium oxalate, and mak- 
ing a double precipitation. There was obtained .23 per cent of calcium 
oxide more by method A than by B. It is evident, therefore, that when 
the amount of magnesium is relatively large method A is to be preferred. 
An analysis of the magnesite resulted: 
MgCOg 98.43 per cent. 
CaCO s 1.22 per cent. 
Si0 2 0.19 per cent. 
99.84 per cent. 
The specimen was purchased of the dealers and its locality was not 
ascertained. 
* Crooks Select Methods, page 52. 
