SPATE GEOLOGIST: 1383 
evaporation to dryness is unnecessary. The solution is made up to 250 cc. 
in a beaker and boiled. To the boiling solution Io cc. of a saturated 
solution of barium chloride is added slowly, drop by drop, and the boiling 
continued until the precipitate is well formed. It is then set aside over 
night, filtered, ignited and weighed as barium sulphate. 
Total Sulphur.—One gram of the material is weighed out in a large 
platinum crucible and fused with sodium carbonate and a little potassium 
aitrate over a gasoline or alcohol blast lamp. The melt is treated in a 
crucible with boiling water ard the liquid poured into a tall narrow 
beaker and more hot water added until the mass is dissolved.. The 
solution is then filtered. 
The filtrate contained in a No. 4 beaker is acidulated with 
hydrochloric acid, made up to about 250 cc. with distilled water, boiled, 
the sulphur precipitated with barium chloride as barium sulphate and 
allowed to stand over night. 
Loss on Ignition.—One-half gram of cement is weighed out 
in a platinum crucible and blasted for 15 minutes. The loss, which is 
checked by a second blasting, is the loss on ignition. 
RAPID OR FACTORY LABORATORY METHODS. 
In the laboratories of the cement industry the determination of cal- 
cium oxide is, of course, the principal part of the routine work and a 
number of rapid methods for its determination as well as for the estima- 
tion of magnesia have been worked out. These methods are as follows: 
1. Titration of the oxalic acid from the washed precipitate oi 
calcium oxalate, decomposed by acid. 
2. Titration by the use of standard acid and alkali solutions. 
3. Volumetric determination of the carbon dioxide evolved from 
the calcium carbonate. 
4. Volumetric determination of magnesia depending on the fact that 
magnesia is entirely precipitated from a strongly ammoniacal solution, 
as magnesium ammonium arsenate by addition of sodium arsenate. The 
arsenic is determined volumetrically and the magnesium calculated 
from it.* ° 
Method 4{.—In American practice the first method is used most 
commonly and seems to enjoy the greatest favor among cement chemists. 
It requires a potassium permanganate solution of such strength that 1 cc.= 
0.005 gram calcium carbonate or calcium oxide, depending on whether a 
raw mixture or burnt cement is to be analyzed. The method is carried out 
for limestone as follows: 
Weigh out 0.5 gram of the finely ground sample into a platinum 
crucible and ignite over the Bunsen burner to destroy all organic matter. 
*“R, K. Meade, The Chemical and Physical Examination of Portland Cement,” p. 42. 
