BORON. RAMSAY. 143 



Crookes, abominably bad in this point. This identical 

 recommendation was made in the first edition of Clarke, 

 1887, P- 95- We have quoted it, p. 122, lowest line. 



Ramsay and Aston's Weighings, in Grammes. 

 No. Na2 O? Bo4. Na Cl. Analyt. Ratio. Excess. 



Extremes 968 900; range 68. 



Mean 0.57 930 9 high. 



It will be observed that this admirable series of analyt- 

 ical determinations deviates in the sense indicated (high) ; 

 however, two of the five determinations are low, showing 

 that the errors have actually fallen on both sides of the 

 atomic ratio! 



It is this last fact that gives special value to this series, 

 which also is noted for the very small constant error in the 

 direction foreseen by the trifling action on the glass. 



It will be very interesting to obtain a more readily com- 

 prehensive idea of the precision attained in this work. 



As stated, change of boron to n.i would lower the ratio 

 115. Accordingly n.oi corresponds to 12 low, and 11.001 

 to i low. 



Since the individual determinations fall practically evenly 

 on both sides of our standard high and low, bearing in mind 

 the minute constant error known to make high, we can say 

 that the true atomic weight of boron is proved not to deviate 

 as much as 0.005 from the standard 1 1 exactly. 



It must therefore be recognized that the five analytical 

 ratios determined in the final series of Ramsay and Aston, 

 being determinations Nos. 22 to 26 inclusive, authorize us 

 to declare that the absolute, true atomic weight of boron is 

 ii exactly (diamond-carbon being 12 exactly). 



