436 PRINCIPLES OF CHEMISTRY 



132-843 of silver chloride. The second method consisted in dissolving 

 a given quantity of silver in nitric acid and precipitating it by means 

 of gaseous hydrochloric acid passed over the surface of the liquid ; the 

 resultant mass was evaporated in the dark to drive off the nitric acid 

 and excess of hydrochloric acid, and the remaining silver chloride was 

 fused first in^an atmosphere of hydrochloric acid gas and then in air. 

 In this process the silver chloride was not washed, and therefore there 

 could be no loss from solution. Two experiments made by this 

 method showed that 100 parts of silver give 132-849 and 132-846 

 parts of silver chloride. A third series of determinations was also 

 made by precipitating a solution of silver nitrate with a certain 

 excess of gaseous hydrochloric acid. The amount of silver chloride 

 obtained was altogether 132-848. Lastly, a fourth determination was 

 made by precipitating dissolved silver with a solution of ammonium 

 chloride, when it was found that a considerable amount of silver 

 (0-3175) had passed into solution in the washing; for 100 parts 

 of silver there was obtained altogether 132-8417 of silver chloride. 

 Thus from the mean of seven determinations it appears that 100 

 parts of silver give 132 '8445 parts of silver chloride that, is, that 

 32-8445 parts of chlorine are able to combine with 100 parts of 

 silver and with that quantity of sodium which is contained in 

 54-2078 parts of sodium chloride. These observations show that 

 32-8445 parts of chlorine combine with 100 parts of silver and 

 with 21-3633 parts of sodium. From these figures expressing the 

 relation between the combining weights of chlorine, silver, and sodium, 

 it would be possible to determine their atomic weights that is, the 

 combining quantity of these elements with respect to one part by 

 weight of hydrogen or 16 parts of oxygen, if there existed a series of 

 similarly accurate determinations for the reactions between hydrogen 

 or oxygen and one of these elements chlorine, sodium, or silver. If 

 we determine the quantity of silver chloride which is obtained from 

 silver chlorate, AgClO 3 , we shall know the relation between the 

 combining weights of silver chloride and oxygen, so that, taking the 

 quantity of oxygen as a constant magnitude, we can learn from this 

 reaction the combining weight of silver chloride, and from the preced- 

 ing numbers the combining weights of chlorine and silver. For this 

 purpose it was first necessary to obtain pure silver chlorate. This 

 Stas did by acting on silver oxide or carbonate, suspended in water, 

 with gaseous chlorine. 26 



26 The phenomenon which then takes place is described by Stas as follows, in a manner 

 which is perfect in its clearness and accuracy : if silver oxide or carbonate be suspended 

 in water, and an excess of water saturated with chlorine Jbe added, all the silver 



