68 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 54 



Mean of all, 2.14093, ± .000053 

 Reduced to vacuo, 2.1394 



From the sums of the weights Thomsen finds the ratio to be 2.14087, 

 or 2.13934 in vacuo. 



ANALYSES OF CHLORATES. 



Until recent times the fundamental values for the atomic weights of 

 silver, chlorine and potassium, were best determined by analyses of 

 chlorates. Modern, direct determinations of the chlorine-hydrogen and 

 nitrogen-oxygen ratios have in great measure supplanted the chlorate 

 work, which, however, must still be taken into account, and may even 

 regain some of the lost ground. 



The first good series of analyses of potassium chlorate was made by 

 Berzelius/ All the earlier estimations were vitiated by the fact that 

 when potassium chlorate is ignited under ordinary circumstances a 

 little solid material is mechanically carried away with the oxygen gas. 

 Minute portions of the substance may even be actually volatilized. These 

 sources of loss were avoided by Berzelius, who devised means for collect- 

 ing and weighing this trace of potassium chloride. All the successors 

 of Berzelius in this work have benefited by his example, although for the 

 methods by which loss has been prevented we must refer to the original 

 papers of the several investigators. In short, then, Berzelius ignited 

 potassium chlorate, and determined the percentage of chloride which 

 remained. Pour experiments gave the following results : 



60.854 

 60.850 

 60.850 

 60.851 



Mean, 60.851, ± .0006 



^ Poggend. Ann.i>cn, 8, 1. 1826. 



