66 Mr. S. B. McLaren on the Emission and 



dihydrol and of dihydrol into hydrol. The main difficulty 

 encountered in the inquiry is that the physical properties of 

 hydrol are not so nearly constant as those of ordinary sub- 

 stances. In connexion with solid hydrol in water o£ 

 crystallization this has already been found to be the case. 

 Hydrol dissolved in a great excess of alcohol seems to have a 

 different density from that when it is dissolved in excess of 

 acetic acid or that deduced for it in the liquid state from its 

 density as a solid in water of crystallization. When hydrol 

 is dissolved in alcohol and in acetic acid it has a different 

 (n 2 — l)/(n 2 + 2)p from that found in water of crystallization. 

 This variation in the properties of hydrol I ascribe to the 

 fact that the atom in H 2 has at least one electric doublet 

 #t> of variable moment, variable according to the electric 

 properties of the molecules surrounding it. The properties 

 of the hydrol molecule are more dependent on its environ- 

 ment than is usually the case. The view that H 2 0#t> has 

 varying properties according to the relative positions of 

 # and |? is one that should make the investigation of hydrol 

 of representative importance in the study of molecular and 

 atomic architecture. 



Melbourne, March 1911. 



IV. The Emission and Absorption of Energy by Electrons. 

 By S. B. McLaren, M.A., Trinity College, Cambridge, 

 Assistant Lecturer in Mathematics in the University of 

 Birmingham *. 



Contents. 



§ 1. Results and Introduction (p. 66). 



§2. Disturbed Motion due to Radiation (p. 69). 



§ 3. Significance of Wien's Law (p. 70). 



§ 4. The Disturbed Orbits (p. 72). 



§ 5. The Absorption of Radiation (p. 77). 



§ 6. The Emission of Radiation (p. 81). 



§ 7. The Complete Radiation (p. 83). 



§ 1. Results and Introduction. 



LORENTZ'S theory of complete radiation is here extended 

 to all wave-lengths. The negative electrons, moving 

 in any conservative field of force due to the positive 

 charges, absorb energy from the external radiation and by 

 their motion return energy to it. Their velocities need not 

 be small compared with the velocity of light ; the pressure of 



* Communicated by the Author. 



