CHLORINE. CALCULATIONS 145 



Blowing the breath into the jar, afterwards, gives the fog due to 

 hydrogen chloride. Thus the presence of hydrogen and carbon 

 in the wax of the taper is proved. From this we learn, also, that 

 chlorine has a relatively small tendency to combine with carbon. 

 A few drops of warm turpentine (Ci Hi 6 ) upon a slip of filter paper 

 will blaze up in chlorine, giving hydrogen chloride and an immense 

 cloud of soot: 



Skeleton: C 10 H 16 + Cl 2 - C + HC1. 



Balanced: Ci H 16 + 8C1 2 - IOC + 16HC1. 



Acts upon Water. We have seen that chlorine acts on 

 steam, reversing Deacon's . reaction to the extent of 20 per cent. 

 It acts also upon cold water, when dissolved in the latter, although 

 in a similarly incomplete way. With half-saturated chlorine- 

 water at 10, about one-third of the chlorine is transformed. 

 One of the products, hypochlorous acid HOC1, is of especial 

 interest, because it is an exceedingly active substance, much used 

 as an oxidizing agent (see p. 223) and for bleaching: 



Cls + H,0<=HCH-HOCl. 



Unites with Non-metals. Phosphorus burns in the gas, 

 giving the vapor of phosphorus trichloride PCls. This substance, 

 with excess of chlorine, forms the pentachloride PC1 5 . When 

 phosphorus pentachloride is heated, it vaporizes and dissociates 

 again partially into the trichloride and chlorine, according to the 

 reversible reaction: 



PC1 5 ^ PC1 3 + C1 2 . 



Sulphur, when heated with chlorine, combines slowly, giving sul- 

 phur monochloride S 2 C1 2 , used in vulcanizing rubber. 



Although chlorine does not combine very readily with carbon, 

 several compounds of carbon and chlorine are very important, 

 such as chloroform CHC1 3 , carbon tetrachloride CC1 4 (p. 332) 

 and phosgene COC1 2 (p. 484). 



