64 LETTEKS OF BEEZELIUS 



loses them so soon as it is brought in contact 

 with oxidizable substances, e.g., sulphurous 

 acid or metals. 



12. Even mercury reacts in this way, with the 

 formation of a mercury salt soluble in water. 



If hydrogen is burned in atmospheric air and the 

 following liquids are held over the point of the flame 

 in narrow tubes, the following reactions take place : 



1. Indigo solution becomes decolorized. 



2. Iodine is liberated from potassium iodide and 



hydrogen iodide solutions or paper moistened 

 with starch paste and potassium iodide be- 

 comes blue. 



3. A potassium ferrocyanide solution assumes an 



intense yellow coloration, is, in fact, converted 

 into potassium ferricyanide. 



. 4. White ferrous cyanide suspended in water turns 

 dark blue. 



5. A ferrous salt in solution is converted into a 



ferric salt. 



6. Aqueous sulphurous acid is transformed into 



sulphuric acid. 



7. Lead sulphide suspended in water is bleached. 



A slip of paper saturated with water and 

 coloured brown with lead sulphide turns 

 white on being held over the point of the 

 flame. 



