44 THE ATOMIC WEIGHTS. 



10.700 grm. KCl gave 20.627 ^SCI. 192.776 



10.5195 " 20.273 " 192.716 



8.587 " 16.556 " 192.803 



Mean, 192.765, d= .017 



The three series of ten experiments in all foot up thus : 



Maiignac, 1842 192.260, zb .003 



" 1846 ,. 192.349, rfc .006 



Maumene 192 765, zh .017 



General mean 192.294, zb .0029 



These figures show clearly that the ratio which they represent is not 

 of very high importance. It might be rejected altogether without im- 

 propriety, and is only retained for the sake of completeness. It Avill 

 obviously receive but little weight in our final discussion. 



In estimating the atomic weight of bromine the earlier experiments of 

 Balard, Berzelius, Liebig, and Lowig may all be rejected. Tlieir results 

 were all f^ir too low, probably because chlorine was present as an im- 

 purit}^ in the materials employed. Wallace's determinations, based upon 

 the anal3^sis of arsenic tribromide, are tolerably good, but need not be 

 considered here. In the present state of our knowledge, Wallace's 

 analyses are better fitted for fixing the atomic weight of arsenic, and 

 will, therefore, be discussed with reference to that element. 



The ratios with which we now have to deal are closely similar to those 

 involving chlorine. In the first place, there are the anal3''ses of silver 

 bromate b}^ Stas.^ In two careful experiments he found in this salt the 

 following percentages of oxygen : 



20.351 

 20.347 



Mean, 20.349, dz .0014 



There are also four analyses of potassium bromate by Marignac.f The 

 salt was heated, and the percentage loss of ox3^gen determined. Thfe 

 residual bromide was feebly alkaline. We cannot place much reliance 

 upon this series. The results are as follows : 



28 7016 

 28.6496 

 28.6050 

 28.7460 



Mean, 2S.6755, rb .0207 



*Aronstein's translation, pp. 200-206. 



tSee E. Mulder's Overzigt, p. 117 ; or Berzelius' Jahresbericht, 24, 72. 



