300 



On Chemical Tests. 



[Oct. 



lized; if baryta or strontiabe present, they must both be removed previ* 

 ously by sulphuric acid. The following numbers should also be referred 

 to, as sulphuric acid acts on solutions of lime, as well as on baryta and 

 strontia; \S,b,c,d: 40: 44: 72: 115. The presence of other earths in 

 solution along with lime impedes decomposition by oxalic acid, and the 

 oxalates. Thus a watery solution of sulphate of magnesia and sulphate 

 of lime is not precipitated by these tests. 



3S. AMMONIA, succinate of acts like the succinate of sod ), which 

 detects the peroxide, but not the protoxide of iron, occasioning a brown 

 precipitate. It precipitates also alumina, if the solution be not too ac id. 

 Succinate of ammonia throws down glucina, ziiconia and baryta. See 

 115 c. Both the succinates are useful in separating peroxide of iron 

 from the oxide of manganese; the iron however re-dissolves in an excess 

 of the precipitant. 



37. ANIMAL MATTER is detected by nitric acid, which occasions 

 it, with cold digestion, to give ofFjnitrogen. Animal matter is thus dis- 

 tinguished from vegetable matter. 



38. antimony ; solutions of the protoxide of antimony which are 

 usually of a brownish yellow colour, are best and- most readily known by 

 their action with hydrosulphuret of ammonia, which produces a red preci- 

 pitate, completely soluble in an excess of the precipitant ; and by liquid 

 sulphuretted hydrogen^ or sulphuretted hydrogen gas, either of which oc- 

 casions both in acid and neutral solutions, a red precipitate. If there 

 should be at first merely a red colour in neutral solutions the precipitate, 

 is immediately produced by adding muriatic acid, or by heating the so- 

 lution. 



a. Metallic zinc precipitates antimony in a black metallic powder. 

 Tin also precipitates it. 



b. Before the blow-pipe with soda, the salts of antimony are reduced 

 in the inner flame, and the bead of metallic antimony remains long in the 

 melted state after being removed from the flame, and gives off' a thick 

 white smoke. Afterwards the bead is covered with a net work of crys- 

 tals of protoxide of antimony. 



c. Potash, ammonia, carbonate and bicarbonate of potash, carbonate 

 of soda, phosphate of soda, oxalic acid, gallic acid, prussiate of potass, all 

 produce a white precipitate insoluble in excess of the precipitant. Wa- 

 ter produces a white precipitate which is a disalr. 



d. Neither nitric, sulphuric, phosphoric, nor carbonic acid forms 



