128 



RESEARCHES UPON ATOMIC WEIGHTS. 



pentoxide, about 350", with a Bunsen burner. Decomposition was conducted 

 as evenly as possible so as to avoid an unduly rapid current of oxygen from the 

 apparatus with consequent incomplete absorption of the water. When decom- 

 position was complete the condensed iodine was heated above its melting-point 

 to set free traces of absorbed moisture. Then the decomposition tube was swept 

 out with a current of dry air and the absorption tube was weighed. In four 

 experiments carried out as above the following results were obtained: 



In addition, several experiments were performed in order to determine the 

 effect of varying the conditions of treatment. In analysis 5 the heating at 240" 

 lasted only one hour, and in analysis 6 the iodine pentoxide was heated for four 

 hours at 260°. In analyses 7 to 11 only a very small quantity of the second 

 phase was used to inoculate the pentoxide; in analyses 7 and 8 the substance 

 was powdered to the same degree of fineness as in the first set of experiments; in 

 analysis 9 the material was very finely powdered, and in analyses 10 and 11 the 

 material was rather coarsely powdered. 



The differences in composition of the pentoxide actually observed, even with 

 very widely differing methods of treatment, are so small that there can be no 

 doubt that the slight variations in treatment likely to occur in the course of an 

 analysis could not have had an appreciable effect. 



