ay ANNUAL REPORT 
grams of potassium acid sulphate, the melt taken up with hot water and 
25 cc. dilute sulphuric acid. The clear solution is then digested on the 
steam bath for about 10 minutes, and if great accuracy is desired the small 
amount of silica filtered off, weighed and corrected with hydrofluoric acid 
and sulphuric acid. ‘The filtrate is reduced by hydrogen sulphide, boiling 
out the excess afterwards while passing carbon dioxide through the 
flask, and titrated with potassium permanganate. This procedure elim- 
inates the influence of titanium. | 
Lime.—To the combined filtrate from the alumina and ferric oxide a 
few drops of ammonium hydroxide are added and the solution brought to 
boiling. To the boiling solution 20 cc. of a saturated solution of am- 
monium oxalate is added and the boiling continued until the calcium 
oxalate appears as a well defined granular precipitate. It is allowed to. 
stand for 20 minutes or until the precipitate has settled and then filtered. 
The precipitate and filter are placed, wet, in a platinum crucible and the 
paper burnt off over a small Bunsen flame. It is then ignited, redissolved 
in hydrochloric acid and the solution made up to about 100 cc. with water. 
Ammonia is added in slight excess and the liquid boiled. The small 
amount of alumina which is separated is filtered and weighed, and the 
amount added to that found in the first determination, when great ac- 
curacy is desired. The lime is then reprecipitated by ammonium oxalate, 
allowed to stand until settled, washed, weighed as oxide by ignition 
and blasting to constant weight or determined with a standard potassium 
permanganate solution, which method, however, is somewhat questionable 
as to accuracy. 
Magnesia.—The combined filtrates from the calcium precipitate are 
acidified with hydrochloric acid and concentrated on the steam bath to 
about 150 cc. 30 cc. of a saturated solution of Na(NH,)HPO, are 
added and the solution boiled for several minutes. It is then removed and 
cooled by placing the beaker in ice water. After cooling ammonia is 
added, drop by drop, until the crystalline ammonium magnesium ortho- 
phosphate begins to form, and then in slight excess with constant stirring. 
It is then set aside for several hours in a cool atmosphere and filtered. 
The precipitate is redissolved in hot hydrochloric acid, the solution made 
up to about 100 cc., 2 cc. of a saturated microcosmic salt solution added 
and ammonia, drop by drop, with constant stirring until the precipitate 1s 
again formed as described. Allow to stand for about two hours, when 
it is filtered on paper or in a Gooch crucible, cooled and weighed as mag- 
nesium phosphate. 
Alkalies.—These are determined by the J. L. Smith method, with or 
without addition of calcium carbonate to the ammonium chloride. 
Sulphur Tri-Oxide (SO,)—One gram of cement is dissolved in 
15 cc. of hydrochloric acid, filtered, and the residue washed thoroughly ; 
