1839.] 



On Chemical Tests. 



rn 



xxxvii. k, Add carbonate of potash, or of soda; if the precipitate is 



First white, then green and} 

 finally brownish red at the > the base is Protoxide of iron. 

 surface. ) 



Dirty red do. ...Oxide of cobalt. 



Bright green do/ ...Oxide of nickell. 



xxxvrii. I. Add hydrosulphuret of ammonia : if a flesh-red precipitate 

 occurs, the base is protoxide of manganese ; but if it is white, the base 

 will be either zinc, or alumina. They may be distinguished thus : 



xxxix. m. Supersaturate with caustic ammonia, and if the white preci- 

 pitate re-dissolves on adding the ammonia, the base is oxide of zinc 

 but if it does not, the base is alumina. 



xl. Note. — If strontia, barytes, lime and magnesia be present in 

 combination with phosphoric, or boracic acid, or when their metallic 

 bases are combined with fluorine, they may also be precipitated by 

 caustic ammonia. Phosphoric and boracic acid and fluorine ought not 

 therefore to be present when ammonia is used, nor ought indeed mag- 

 nesia by itself simply, fur magnesia is also precipitated by caustic am- 

 monia. 



xli. Third. — If the acid solution does not give a precipitate with 

 liquid sulphuretted hydrogen : nor the neu- 

 l.f?da! h ' | Li r m°e ntian ' *ral solution with hydrosulphuret of am- 

 4B^j m t2s'" a ' 7 - Ma = ne5ia - monia, the base is not included in Nos. 8 

 to 25. but in Nos. 1. to 7. 



xL.li. 7i. Add to the neutral solution, carbonate of potash. If a white 

 precipitate occurs, the base is from Xo. 4 to 7. To discriminate which, 

 observe that a white Succulent precipitate indicates magnesia : but if 

 only after some time a precipitate is formed, the base is barytes. If no 

 precipitate appears, the base is either lime, or strontian. 



xliii. o. To distinguish between lime and strontian, dilute the neu- 

 tral solution with a large quantity of water, and test with a few drops 

 of sulphate of potash, or very dilute sulphuric acid. If a precipitate 

 is immediately produced, the base is strontian ; but if no immediate pre- 

 cipitate takes place, but after some time a crystalline precipitate ap- 

 pears, the base is lime. 



xxiv. Fourth. — If neither liquid sulphuretted hydrogen; hydrosul- 

 phuret of ammonia ; nor carbonate of potash gives a precipitate, the 

 substance must be from 1 to 3, that is, potash, soda, or ammonia. 



xlv. p. To distinguish these ; concentrate the solution. Add con- 

 centrated caustic potash, and hold over the liquid, a rod dipped in mu- 

 riatic acid j if white clouds appear, the base is ammonia. 



xlvl q. Add to another portion of the concentrated solution, chloride 



