10 More about Argon. [Jan. 17, 



bility of helium in water is only * 007, less than one-fifth of that 

 which we found for argon.* 



It is evident that if a mixture of helium and argon be dissolved 

 in water until there is only a small fraction remaining over, the 

 proportion of helium will be much increased in the residue. Two 

 experiments have been made, of which that on October 6, 1805, 

 was the more elaborate. About 60 c.c. of argon were shaken for 

 a long time with well boiled water contained in a large flask. 

 When the absorption had ceased, the residue of 30 c.c. was sparked 

 with a little oxygen until no nitrogen could be seen in the spec- 

 trum. It was then treated a second time with boiled water until its 

 volume was reduced to 1 J c.c. With this vacuum tubes were charged 

 by my son at two different pressures. In none of them could D3 be 

 detected ; nor was there any marked difference to be seen between 

 the spectra of the washed and the unwashed argon. If helium be 

 present in the atmosphere, it must be in very small quantity, pro- 

 ably much less than a ten-thousandth part. 



* Phil. Trans. A, vol. 18G, p. 225, 1895. 



