230 ARSENIC. 



give values reduced to vacuum, and base the atomic weight 

 of arsenic thereupon. 



By comparing these values with ours (the direct weigh- 

 ings in air), it will be seen that the analytical ratios reduced 

 to vacuum are in 



No. i 2345 6 7 8 9 10 

 31 7 o 7 17 i i 4 i i 



low low low low high low low high low low 

 compared to our direct ratios. 



This shows that for the first five determinations, in which 

 the smallest amount of substance was used (less than half a 

 gramme), these reductions are the largest and the most 

 fluctuating, showing an absolute range of 48 units in the 

 fifth place. 



The corresponding fluctuation in the resuJting atomic 

 weight is four-thirds of a unit. 



For the larger amount of substance (exceeding half a 

 gramme) the reduction to vacuum is the least and fluctuates 

 least, the total range being only 5 units in the fifth 

 decimal. 



This corresponds to only about 0.013 on the atomic weight 

 of arsenic. 



We notice plainly the enormous " high " in No. 5 and 

 the next in No. 8, and particularly the excessive low in No. i. 



These results show that in the new Chemical Laboratory 

 of the University of Pennsylvania, the floor has already 

 begun to give way very much, as it did in the laboratory of 

 Stas, at Brussels. 



If the Stasian Errors are not definitely removed from 

 this new American Laboratory, Professor Edgar F. Smith 

 may next time find himself several thousand yards down in 

 the earth as did Stas in his No. 6. 



And if Professor Smith continues to use the false Smith- 

 sonian Atomic Weights of Clarke, in his American Labora- 

 tory, I shall have to leave him in that hole. 



I hope that Professor Edgar F. Smith also will discon- 

 tinue this humbug of reduction to vacuum. See p. 175. 



