96 SULPHUR. MARCHAND. 



The chemical process here expressed in standard atomic 

 weights gives the atomic ratio stated. 



The individual determinations are all high, but in the 

 order of record only i, 4, u, 13, 4 high in fifth place. 



The mean is only 7 high; the range only i2_, the extremes 

 being 606 594. 



As the range 12 includes the deviation 7, the data of the 

 experiments do not allow to depend upon this mean deviation. 

 Furthermore, while the individual deviations are all high, 

 the smallest brings the result to -within a single unit in the 

 fifth place. 



The experimental data do not establish any deviation 

 from the standard atomic weight 200, which therefore is the 

 true atomic weight of mercury. 



If we were to follow the erroneous process of calculating 

 atomic weights to decimals not determined by the precision 

 of the experiments, the mean would give us 200.2; but the 

 range 12 corresponds to an uncertainty of 0.4, and thus 

 shows the fallacy of such calculation. 



V. THE ATOMIC WEIGHT OF SULPHUR. MARCHAND. 



Erdmann and Marchand also distilled mercury from pure 

 mercuric sulphide mixed with copper. The following are 

 the weights and the analytical ratios t 



The chemical process here expressed in standard atomic 

 weights gives the atomic ratio stated. For one tenth added 

 to the 200 of mercury, the atomic ratio would rise 7 or be 

 7 high. 



The mean analytical ratio is only 6 high. The extremes 

 are 223 206, giving a range of 17. 



