DETECTION OF THE BASIC ELEMENTS. 139 



drate to the filtrate, to bo sure that no further pre- 

 cipitation will be produced, then add ammoiiic 

 carbonate as long as a precipitate is formed, avoid- 

 ing, however, a great excess of the reagent, heat 

 and filter, and evaporate the filtrate nearly to 

 dryness. 



A drop of this filtrate, evaporated to dryness in 

 the platinum wire loop, gives a yellow color to the 

 flame of a Bunsen's gas-burner. Sodium. - - - 9 



9. "in a similar experiment the flame is violet, or vio- 

 let-red when seen through blue glass. Potassium. 10 



10. To a small portion of F. 3, add ammonia very 

 carefully until the free acid is just neutralized, and 

 then a little ammonic sulphide, drop by drop, with 

 constant agitation, and heat the mixture. 



a. No precipitate is formed at any time. (Traces v 

 of copper, arsenic, iron, and manganese, may per- 

 haps be found by applying the tests described in 

 10 b, 12, 14, and 15 ^>). 18 



Z>. A precipitate is formed. 



To a small portion of F. 3, add ammonia until the 

 well-mixed liquid smells strongly of the reagent, 

 and let the precipitate settle if any is formed. The 

 clear supernatant liquid is blue. Coppee. - - 11 



11. In the same experiment a red flocculent precipi- 

 tate is obtained, the color of which may, however, 

 not appear, in case much copper is present, until it 

 has been collected on a filter and washed a few 

 times. Ieon. 1^ 



12. If copper has been found in notable quantity, put 

 the remainder of F. 3 in a small flask, add two 

 or three pieces of pure zinc, and close the flask 

 with a perforated cork, in which is a glass tube 

 drawn out to a fine jet. 



