ATOMIC WEIGHTS 71 



chlorate is ignited slowly, we get GO. 847 per cent, of residue. When the 

 ignition is rapid, we get 60.942. As no detailed experiments are given, 

 these figures can have no part in our discussion. 



Last of all we have two series determined by Stas.' In the first series 

 are the results obtained by igniting the chlorate. In the second series 

 the chlorate was reduced by strong hydrochloric acid, after the method 



followed by Penny: 



First Series. 

 60.8380 



60.8395 , 



60.8440 

 60.8473 

 60.8450 



Mean, G0.S427G, ± .0012 



Second Series. 

 60.850 

 60.853 

 60.844 



Mean, 60.849, ± .0017 



In these experiments every conceivable precaution was taken to avoid 

 error and insure accuracy. All weighings were reduced to a vacuum 

 standard; from 70 to 142 grammes of chlorate were used in each experi- 

 ment; and the chlorine carried away with the oxygen in the first series 

 was absorbed by finely divided silver and estimated. 



According to Guye and Ter Gazarian," potassium chlorate tends to 

 retain a constant impurity of chloride. The average amount of chloride, 

 they say, is 2.7 parts in 10,000, but they give no detailed figures in 

 support of their assertion. It can therefore be given only provisional 

 consideration, the existence of the impurity being not fully established. 

 Leaving their correction temporarily out of account, the different series 

 of determinations of KCl from KCIO3 combine as follows : 



BeiY.elius 60.851, ± .0006 



Penny 60.8225, ± .0014 



Pelouze 60.843, ± .0053 



Marignac 60.8392, ± .0013 



Gerhardt, 1st 60.8757, ± .0020 



2d 60.9487, ± .0011 



Maumene 60.791, ± .0009 



Stas, 1st 60.8428, ± .0012 



" 2d 60.849, ± .0017 



General mean 60.846, ± .00038 



1 Oeuvres Completes, 1, 395-405. 



2 Compt. Rend., 143, 411. 



