§ 48. BARIUM. § 49. CALCIUM. 59 



standard iodized mercurial solution to 100 or 150 c.c. of 

 the distillate, obtained in h or e, or to any clear and color- 

 less solution containing ammonia ; put in another test- 

 tube, containing about 100 c.c. of water, as much of the 

 standard solution of ammonic chloride as is thought nec- 

 essary to give the same shade of color witli the test- 

 liquid, make the volume of this mixture the same as 

 of the other, by addition of water, add 1 c.c. of the 

 iodized mercurial solution, let stand ten minutes, and then 

 compare shades of color ; if not alike, make another more 

 or less diluted portion of the standard ammonic solution, 

 according as the shade of color of the first was too dark 

 or too light, and repeat the test.. (W. A. Miller.) 



BARIUM. Ba. 137. 



48. Compounds o. barium with sulphuric, oxalic, car- 

 bonic, phosphoric, tartaric, and silicic acids, and with flu- 

 orine, are insoluble or sparingly soluble in water. The 

 sulphate and silicate are insoluble in acids. 



Reactions. — Sulphuric acid and all soluble sulphates 

 produce, even in very dilute solutions of barium salts, a 

 finely pulverulent precipitate of baric sulphate, BaSO^, 

 insoluble in acids, except Avhen hot and concentrated, and 

 even then but very sparingly soluble. This sulphate is 

 slightly decomposed when boiled with a solution of sodic 

 carbonate, but is not changed at all if a soluble sulphate 

 is mixed with the carbonate. 



CALCIUM. Ca. 40. 



49. Compounds of calcium with oxalic, carbonic, phos- 

 phoric, tartaric, and silicic acids, and with fluorine, are 

 insoluble or sparingly soluble in water. The tartrate dis- 

 solves in 352 parts of boiling water. The silicate and 

 fluoride are insoluble in acids. Both water and acids dis- 

 solve the sulphate in small quantity. 



