COPPEE, SILVER, AND GOLD 437 



The decomposition of the silver chlorate thus obtained was accom- 

 plished by the action of a solution of sulphurous anhydride on 

 it. The salt was first fused by carefully heating it at 243. The solution 

 of sulphurous anhydride used was one saturated at 0. Sulphurous 

 anhydride in dilute solutions is oxidised at the expense of silver 

 chlorate, even at low temperatures, with great ease if the liquid be 

 continually shaken, sulphuric acid "and silver chloride being formed : 

 AgC103 + 3S0 2 + 3H 2 0==AgCl + 3H 2 SO 4 . After decomposition, the 

 resultant liquid was evaporated, and the residue of silver chloride 

 weighed. Thus the process consisted in taking a known weight of 

 silver chlorate, converting it into silver chloride, and determining 

 the weight of the latter. "The analysis conducted in this manner gave 

 the following results, which, like the preceding, designate the weight 

 in a vacuum calculated from the weights obtained in air : In the 

 first experiment it appeared that 138*7890 grams of silver chlorate 

 gave 103-9795 parts of silver chloride, and in the second experiment 



is converted into chloride, just as is the case with oxide or carbonate of mercury, 

 and the water then contains, besides the excess of chlorine, only pure hypochlorous 

 acid without the least trace of chloric or chlorous acid. If a stream of chlorine be 

 passed into water containing an excess of silver oxide or silver carbonate while the 

 liquid is continually agitated, the reaction is the same as the preceding; silver 

 chloride and hypochlorous acid are formed. But this acid does not long remain in a free 

 state-: it gradually acts on the silver oxide and gives silver hypochlorite, i.e. AgClO. 

 If, after some time, the current of chlorine be stopped but the shaking continued, 

 the liquid loses its characteristic odour of hypochlorous acid, while preserving its 

 energetic decolourising property, because the silver hypochlorite which is formed is easily 

 soluble in water. In the presence of an excess of silver oxide this salt can be kept for 

 several days without decomposition, but it is exceedingly unstable when no excess of 

 silver oxide or carbonate is present. So long as the solution of silver hypochlorite 19 

 shaken up with the silver oxide, it preserves its transparency and bleaching property, 

 but directly it is allowed to stand, and the silver oxide settles, it becomes rapidly cloudy 

 and deposits large flakes of silver chloride, so that- the black silver oxide which had 

 settled becomes covered with the white precipitate. The liquid then loses its bleaching 

 properties and contains silver chlorate, i.e. AgClO 3 , in solution, which has a slightly 

 alkaline reaction, owing to the presence of a small amount of dissolved oxide. In this 

 manner the reactions which are consecutively accomplished may be expressed by the 

 equations : 



6C1 2 + 3Ag 2 O + 8H 2 O = GAgCl + 6HC1O ; 6HC1O + 3Ag 2 O = 3H 2 + 'GAgClO ; 



6AgC10 = 4AgCl + 2AgClO 3 . 



Hence, Stas gives the following method for the preparation of silver chlorate : A slow 

 current of chlorine is caused to act on oxide of silver, suspended in water which is kept 

 in a state of continual agitation. The shaking is continued after the supply of chlorine 

 has been stopped, in order that the free hypochlorous acid should pass into silver 

 hypochlorite, and the resultant solution of the hypochlorite is drawn off from the 

 sediment of the excess of silver oxide. This solution decomposes spontaneously into 

 silver chloride and chlorate. The pure silver chlorate, AgClO 3 , does not change under 

 the action of light. The salt is prepared for further use by drying it in dry air at 150. 

 It is necessary during drying to prevent the access of any organic matter ; this is done by 

 filtering the air through cotton wool, and, passing it over & layer of red-hot copper oxide. 



