METHOD FOR CONCENTRATED POTASH SALTS 557 



25 cubic centimeters of boiling water after the addition of 90 

 milligrams potassium carbonate for the purpose of converting 

 the magnesium and calcium compounds into carbonates. To 

 the hot solution absolute alcohol is added, the flask well shaken 

 and filled to the mark and again shaken for one minute. After 

 filtration 100 cubic centimeters, corresponding to five grams of 

 the salt, are evaporated to dryness in a porcelain or platinum dish 

 after the addition of a few drops of concentrated hydrochloric 

 acid in order to convert any potassium carbonate which may be 

 present into chlorid. The residue is gently ignited and weighed. 

 In this mixture of potassium and sodium chlorids the potassium 

 chlorid may be estimated in the usual way and the sodium chlo- 

 rid determined by difference, or the respective proportions of the 

 two bases may be calculated after the determination of the total 

 chlorin by precipitation with a standard solution of silver nitrate. 



Estimation of Magnesium Chlorid. In order to estimate the 

 amount of magnesium chlorid in high-grade muriate of potash, 

 25 grams of the latter salt are dissolved in a half liter flask and 

 treated with 10 cubic centimeters of a twice normal solution of 

 potash-lye. The flask is filled to the mark with water, thoroughly 

 shaken and its contents filtered. Fifty cubic centimeters of the 

 filtrate are titrated with one-tenth normal sulfuric acid. The 

 calcium compounds which remain in solution do not influence 

 the result. The quantity of magnesium chlorid originally pres- 

 ent corresponds to the number of cubic centimeters of the nor- 

 mal potash-lye which has disappeared in the operation. The 

 reaction which takes place is represented by the following equa- 

 tion : MgCl 2 +2KOH=MgO 2 H 2 + 2KC1. 



Sulfuric Acid in Muriate of Potash. Fifty grams of the sam- 

 ple are dissolved in 500 cubic centimeters of water. After fil- 

 tering, 200 cubic centimeters, equivalent to 20 grams of the sam- 

 ple, are acidified with one cubic centimeter of concentrated hy- 

 drochloric acid and precipitated at boiling temperature with 

 barium chlorid. After standing from 15 to 18 hours the pre- 

 cipitate is separated by filtration and weighed in the usual 

 manner. 



Potassium Sulfate. The quantity of potassium sulfate con- 



