124 THE ATOMIC WEIGHTS. 



KClOy 



41.161 



41193 

 41.149 

 41.126 



Mean, 41.172, d= .009 



From the data given in the earlier paper, if we use our 

 recent values for chlorine, potassium, and oxygen, 



K^Crp, = 293.937, ± -086 

 And from the later, " = 294.159, zb .119 



General mean, " = 294.013, ;h .0697 



Finally, we come to the determinations published by Sie- 

 wert,* whose work does not seem to have attracted general 

 attention. He, reviewing Berlin's work, found that upon 

 reducing silver chromate with hydrochloric acid and al- 

 cohol, the chromic chloride solution always retained traces 

 of silver chloride dissolved in it. These could be precipi- 

 tated by dilution with water ; but, in Berlin's process, they 

 naturally came down with the chromium hydroxide, mak- 

 ing the weight of the latter too high. Hence too large a 

 value for the atomic weight of chromium. In order to find 

 a more correct value Siewert resorted to the analysis of sub- 

 limed, violet, chromic chloride. This salt he fused with 

 sodium carbonate and a little nitre, treated the fused mass 

 with water, and precipitated from the resulting solution the 

 chlorine by silver nitrate in presence of nitric acid. The 

 weight of the silver chloride thus obtained, estimated after 

 the usual manner, gave means for calculating the atomic 

 weight of chromium. His figures, reduced to a common 

 standard, give, as proportiontd to 100 parts of chloride of 

 silver, the quantities of chromic chloride stated in the third 

 of the subjoined columns : 



* Zeitschrift Gesammt. Wissenschaften, 17, 530. 1S61. 



