CHLORINE. 103 



white precipitate is produced, which blackens on the addition 

 of ammonia : 



HgNO 3 + NaCl = NaNO 3 + HgCl. 



3. Add solution of lead acetate : a white precipitate of lead 

 chloride is formed, which is soluble in much water. 



4. To a dry chloride add strong sulphuric acid and heat : 

 vapors of hydrochloric acid gas are evolved, which may be re- 

 cognized by the odor, or by their action on silver nitrate. 



Aqua regia, Nitre-hydrochloric acid (Acidum nitro-hydrochloricum, 

 Nitro-muriatic add). Obtained by mixing 4 parts of nitric acid 

 with 15 parts of hydrochloric acid. 



The two acids act chemically upon each other, forming chloro- 

 nitrous or chloronitric gas, chlorine and water : 



HNO 3 + 3HC1 = 1STOC1 + 2H 2 O + 2C1 ; 

 HNO 3 + 3HC1 = ISTOCLj + 2H 2 O + 01. 



The dissolving power of this acid upon gold and platinum 

 depends on the action of the free chlorine and the action of the 

 chloronitrous and chloronitric gas, both of which part easily 

 with their chlorine. 



Compounds of chlorine with oxygen. There is no method 

 known to combine chlorine and oxygen directly, all the com- 

 pounds formed by the union of these elements being obtained 

 by indirect processes. The oxides of chlorine are the following: 



Hypochlorous oxide, C1 2 O + H 2 O = 2HC1O. 



Chlorous oxide, C1 2 O 3 + H 2 O = 2HC1O 2 . 



Chlorous tetroxide, C1 2 O 4 does not combine with water to form an acid. 



f Not known in the separate "1 



Chloric oxide, C1 2 O 5 but Jn combi Lion + H * " 2HC1O 3' 



Perchloric oxide, C1 2 7 | with ' water . j + H 2 O = 2HC1O, 



All these oxides, as well as the corresponding acids formed 

 by their union with water, are distinguished by the great facility 

 with which they decompose, frequently with violent explosion, 

 for which reason many of their compounds are used in the 

 manufacture of explosive mixtures. 



