332 



On the Separation of the Alkaline Earths. 



acid, and to the solution diluted with water, dilute sulphuric 

 acid is added. The sulphates of baryta and strontia produced 

 are to be separated from the lime by filtration through as small 

 a filter as possible, and which has been previously washed out 

 with dilute nitric acid. AVhen the precipitate is very small in 

 quantity, it is necessary to burn the filter, and then to test the 

 residue on platinum wire in the usual way. When strontia 

 occurs in very small quantity, it will not be precipitated ; but 

 on adding ammonia and carbonate of ammonia, will go down 

 with the lime, from which it can be separated and tested accord- 

 ing to the manner described in the Table. 



Separation of the Alkaline Earths. 

 The carbonates as usually obtained are dissolved in hydro- 

 chloric acid, and to this solution diluted with water, dilute sul- 

 phuric acid is added. 



Precipitate. 



Sulphate of baryta and 

 sulphate of strontia. 



Test on platinum wire 

 in the air-flame : green 

 (baryta), red (strontia). 

 To the original solution 

 add sulphate of strontia. 

 A precipitate indicates 

 the presence of baryta. 



Filtrate. 

 Sulphate of strontia and sulphate of lime. 

 Add ammonia and carbonate of ammonia. 



Precipitate. 

 Carbonate of strontia and carbonate of lime. 

 Collect on a filter and dissolve in a little nitric acid, 

 evaporate to dryness on a water-bath, and treat 

 with a little strong alcohol. 



Residue. 

 Nitrate of strontia. 



Convert into sulphate 

 and test on platinum 

 wire in the flame, after 

 having reduced and sub- 

 sequently moistened with 

 IlCl. Through dilute 

 solution of indigo, 

 Carmine-red ; 

 Strontia. 



Solutio7i. 

 Nitrate of lime. 

 Add oxalate of am- 

 monia. 



Precipitate. 



Oxalate of lime not 

 soluble in acetic acid. 

 Convert into sulphate 

 and test on platinum 

 wire in the flame, after 

 having reduced and sub- 

 sequeutlvmoistened with 

 IlCl. through dilute 

 solution of indigo, 



Olive-green : 

 Lime. 



• The dilute solution of indigo, to distinguish between strontia 

 and lime, is made by diluting the common indigotic acid till it 

 gives with sulphate of lime an olive-green colour, on testing in 

 the manner directed. Care must be taken not to make this 

 solution too dilute, otherwise sulphate of lime appears slightly 

 red through it. It is to be used in the same kind of vessel as 

 the indigo solution for the alkalies. 



In testing for this group, it is necessary to allow the soda. 



