566 MINERALOGY 



in dilute HC1 ; add a drop of dilute H 2 SO 4 ; a white precipitate of 

 BaSO 4 will appear. Filter and test this precipitate on wire for the 

 barium flame. 



Strontium, Sr. Atomic weight, 87.6. Fusing point, 900 C. 



a. Flame. Strontium minerals when heated in the O. F. yield 

 a bright crimson flame. This will be more marked if after the first 

 heating the fragment is moistened with HC1. Care must be taken 

 not to confuse the strontium flame with the lithium flame, or in 

 case HC1 has been used, with the calcium flame, which is yellowish 

 red. Silicates are fused with soda as in the case of barium. 



6. Wet test. Strontium in solution yields a white precipitate 

 of strontium sulphate, SrS0 4 . Insoluble compounds are fused 

 with soda and treated as under barium, b. The precipitate of 

 sulphates may in some cases contain both strontium and barium. 

 In testing it on wire the strontium flame will appear first. After 

 moistening with HC1 strontium will disappear first and the green 

 of barium after continued heating. 



Illustration. Heat a fragment of strontianite, SrC0 3 , in the 

 forceps in the O. F., and observe the bright crimson flame. Place 

 the ignited fragment on turmeric paper, after moistening; it will 

 react 'alkaline. Dissolve a small fragment in 2 cc. of dilute HC1 ; 

 add a drop of H 2 SO4, when a white precipitate of strontium sul- 

 phate, SrSO 4 , will appear ; filter and test it for the flame. 



Calcium, Ca. Atomic weight, 40.07. Fusing point, 780 C. 



a. Calcium salts, especially after moistening with HC1, yield 

 before the blowpipe a yellowish red flame. When the mineral 

 fails to yield the calcium flame, calcium should be separated in the 

 wet way, as in 6. 



6. Wet test. Calcium sulphate is more soluble than either 

 barium or strontium sulphates and is not precipitated from dilute 

 solutions. This condition may be used to make a qualitative sep- 

 aration of calcium from barium and strontium. The solution of 

 the mineral is obtained by fusion with soda, as under barium ; 

 the solution is diluted and dilute H 2 S0 4 is added until a white 

 precipitate no longer forms ; boil and filter ; the calcium will now 

 be found in the filtrate, from which it is separated by evaporation 

 to very small volume and precipitated with concentrated sulphuric 

 acid. The white precipitate of calcium sulphate, CaS0 4 , is tested 

 for the calcium flame, or concentrated solutions before precipitation 

 may be tested directly by moistening a platinum wire with it and 

 holding it in the Bunsen burner flame. 



