56 THE ATOMIC WEIGHTS OF 



As already intimated, this difference is probably very largely 

 due to moisture in the sodium salt. If the discrepancy be entirely 

 due to this cause the amount of moisture may be computed from 

 the ratios. It will be found that the moisture in Ramsay and 

 Aston's sodium chloride may have amounted to 0.214 per cent. 

 One will not go far wrong, therefore, by assuming that the 

 sodium chloride contained approximately 0.2 per cent, of water. 

 This amount may seem high, but is not beyond the range of 

 possibility. 11 



On now applying these corrections, approximations though 

 they be, to expressions (I) and (II) there would result: 



AT 116.908 X (100 -0.3 percent.) T, 1AA m /T \ 



M = i '- or B = 10.901 .... (!A) 



57.933 -0.2 per cent. 



M= 286.674X(70.546-0.3percent.) orB = 10>909 . . (HB) 



100 



These corrections, far from arbitrary, not only harmonize the 

 inconsistent results obtained by Ramsay and Aston, but lead to 

 values which corroborate the figure found in the present investiga- 

 tion (10.900). The agreement thus established is striking. 



The argument may be supported in still another manner, as 

 follows: If Ramsay and Aston's weight of their "anhydrous" 

 borax be allowed to stand as recorded by them and the hypo- 

 thetical correction (0.2 per cent.H 2 0) be applied only to their 

 sodium chloride there would follow : 



M- " 6 - 908 * 100 or B = 11.052 . . (IB) 

 57.933 -0.2 per cent. 



It has been shown (see p. 43) that if such insufficiently dried 

 borax and a water-free end-product had been used in the calcula- 

 tions the result for boron would have been 10.999. In this case 

 the "borax glass" would have contained approximately 0.2 per 

 cent, of water. In the last column in table 2 it has also been shown 

 that if our own borax glass, other things being equal, had con- 

 tained as much as 0.3 per cent, of moisture (the amount probably 



11 See preceding note. In the present case part of this moisture may have been held 

 in combination with the trace of silica resulting from the etching of the glass 

 vessel, for drying at 350 would not have been sufficient to completely dehy- 

 drate silicic acid. 



