INCRUSTATIONS FROM SALT-PANS. 215 



V. The very small quantity of potassa which is 

 usually present, may be detected by concentrating the 

 solution of a large quantity of the salt so that a great 

 part of the chloride of sodium may crystallize out ; the 

 potassium is then precipitated from the mother-liquor 

 with bichloride of platinum. 



VI. The bromine may be detected by passing chlo- 

 rine into the mother-liquor obtained from a large 

 quantity of the saline solution, and agitating the liquid 

 with ether, which takes up the bromine, and thence 

 acquires a yellow color. The bromine may then be 

 converted into bromide of ammonium by adding am- 

 monia. 



VII. In order to detect the iodine, the mother-liquor 

 is mixed with some starch-paste, and weak chlorine- 

 water added drop by drop ; or the vapor of bromine 

 or of nitrous acid may be allowed to flow on to the 

 surface of the mixture. 



For the quantitative determination of iodine and 

 bromine, see No. 113. 



115. INCRUSTATIONS FROM SALT-PANS. 



NaCI NaO, SO,, CaO, SO 3 , MgO, SO,, CaO, C0 2 , 

 MgO,C0 2 . 



I. A weighed portion is heated nearly to redness in 

 order to determine the water. 



II. Another portion is finely powdered and boiled 

 with water, the residual carbonates of lime and mag- 

 nesia filtered off, washed with hot water, and the two 

 bases separated as in No. 12. This residue sometimes 

 contains iron and manganese. 



III. The filtrate is mixed with chloride of ammo- 

 nium, and the lime precipitated by oxalate of ammo- 

 nia. (See No. 12.) . 



