PROCEEDINGS OF THE OHIO ACADEMY OF SCIENCE. 375 



and thorium and their disintegration products. Sodium and 

 potassium have been reported as radioactive but there is some 

 doubt as to the accuracy of this report. Ramsey has also reported 

 that hthium is a disintegration product of copper but his ex- 

 perimental results have been strongly questioned and are today, 

 I think, not generally accepted. 



Discovery of Argon and its Congeners. It this connection 

 mention should be made of the discovery of the element argon 

 by Lord Rayleigh and Ramsey ; also of the elements helium, neon, 

 krypton and xenon by Ramsey and Travers. All of these ele- 

 ments are found in small c[uantities in the air and are unique 

 in that they are devoid of chemical affinity. Their discovery 

 has made necessary the addition of another group to. the table of 

 the periodic arrangement of the elements. 



Solutions. The general phenomena attending the formation 

 of solutions as well as the properties of the solutions themselves 

 have been the subject of extended investigations. As our ideas 

 concerning the composition of substances developed it was ob- 

 served that solutions differed from mixtures in that they were 

 homogeneous ; and from chemical compounds in that their com- 

 position could be varied within wide limits. It was also observed 

 that solutions possess certain fundamental properties in common. 

 For example, the freezing* point of a solution is lower than that 

 of the pure solvent while the boiling point is higher; moreover, 

 each individual solution possesses a certain definite osmotic 

 pressure. More recently it was discovered that the magnitude 

 of the changes in the boiling points, the freezing points and the 

 osmotic pressure is in each case a function of the number of 

 molecules of the dissolved substances present in the solution. In 

 order, therefore, that solutions of different solids in the same 

 liquid may have the same boiling points, the same freezing points 

 and the same osmotic pressure, it is essential that the solutions 

 contain not equal masses of the solids but masses proportional 

 to the molecular weights of the solids. 



It was known, however, that certain compounds (acids, bases 

 and salts) when dissolved in water form solutions that conduct 

 the electric current (electrolytes), and that in all such solutions 



