124 ABSOLUTE ATOMIC WEIGHT. 



The ratio stated for 100 parts of thallium we convert, by 

 moving the point, to our usual analytical ratios ; here the 

 Amount of thallium nitrate obtained from one unit of 

 metallic thallium. 



These analytical ratios are given to 6 places. Droping 

 the last decimal, being visibly worthless, and observing 

 common restrictions, we have our own five place analytical 

 ratios. 



The mean of the ten ratios is 1.30 391 ; extremes are 393 

 and 388, giving a range of only 5 in the fifth place. That is 

 an extremely minute range. The concordance of the deter- 

 minations is truly remarkable. 



The chemical process, expressed in our Standard Atomic 

 Weights is 



Tl Oa N : Tl 1=266 : 204=3 1.30 392. Chg. 15 low. 



Now it is passing strange that the analytical ratio of a 

 series of ten determinations made in London in 1873, should 

 within a single unit in the fifth decimal agree with our 

 absolute atomic ratio. 



Did Mr. William Crookes undertake this work to prove 

 that our " theory " is correct? Hardly, as he but a few years 

 previously had held up to public ridicule our " Programme " 

 of Atom-Mechanics, while showing in his abusive paper 

 that he certainly had not read it. He simply tried to mis- 

 lead his subscribers and thus to defraud them. 



But really, the case is still more astonishing. For upon 

 closer examination of the ratios we notice that only the first 

 is two below 390; we might, therefore, exclude it as the first, 

 not quite successful effort made. We want to treat Mr. 

 William Crookes kindly. But at the same time we must say 

 that the total weight of thallium used in No. i is by far the 

 highest. We shall have to come back to this point. 



In ordinary determinations, where even fine work is 

 done, we would not mind a variation of two units in the fifth 

 decimal. But here we have something extraordinary indeed 

 in apparent precision. Therefore, let us drop this deviating 

 determination as due to the first trial of a master workman. 



There then remain 9 determinations. Now all 9 ana- 

 lytical ratios are identical in the first five digits, 1.3039. 



