242 THE ATOMIC WEIGHTS. 



Ill his earlier paper* the mode of procedure was about as follows: 

 The two salts, weighed out in quantities having approximate chemical 

 equivalency, were placed in two small flasks, and to each was added 

 100 cc. of a ferrous chloride solution and 30 cc. hydrochloric acid. The 

 ferrous chloride was added in trifling excess, and, wlien action ceased, 

 the amount unoxidized was determined by titration with a standard solu- 

 tion of dichroniate. As in each case the quantity of ferrous chloride was 

 the same, it became easy to deduce from the data thus obtained the ratio 

 in question. I have reduced all of his somewhat comj^licated figures to 

 a simple common standard, and give below the amount of chromate 

 equivalent to 100 of cldorate: 



1 20.118 



120.371 



120.138 



120.096 



120.241 



120. 181 



Mean, 120. 191, rfc .028 



In his later paper t Kessler substituted arsenic trioxide for the iron 

 solution. In one series of experiments the quantity of dichromate needed 

 to oxidize 100 parts of the arsenic trioxide was determined, and in an- 

 other the latter substance was similarly compared with the chlorate. 

 The subjoined columns give the quantity of each salt proportional to 100 

 of As.Og : 



K,,Cr^O,. KCIO.,. 



98.95 41.156 



98.94 41. 116 



99.17 41.200 



98.98 41.255 



99.08 41.201 



99.15 41.086 



41.199 



Mean, 99.045, ± .028 41.224 



4X.161 

 41.193 

 41.149 

 41.126 



Mean, 41. 172, rb .009 



Reducing the later series to the standard of the earlier, the two com- 

 bine as follows : 



(1) 2KCIO.5 : KjCr.^O, : : 100 : I20. 191, ± .028 



(2) 2KCIO3 : KjCr/J), : : 100 : 120.282, ± .043 



General mean 120.216, ± .0235 



* Poojgend. Annalen, 95, 208 1855. 

 tPoggen4. Annalen, 113. 137. i86r. 



