These numbers show that the solution of the sulphate of cop- 

 per transmits rays of the line G, which is found at the limits of 

 the indigo and violet; that the light of saline alcohol corre- 

 sponds sensibly to the line D ; and finally, that the two super- 

 posed red glasses transmit rays which are found in the spectrum 

 far beyond the extreme red of Fresnel, without attaining, how- 

 ever, the extreme red of Fraunhofer. 



[To be continued.] 



XXXIV. On some Extensions of Quaternions, By Sir William 

 Rowan Hamilton, LL.D., M.R.I.A., F.R.A.S., Correspond- 

 ing Member of the French Institute, Hon. or Corr. Member of 

 several other Scientific Societies in British and Foreign Coun- 

 tries, Andrews* Professor of Astronomy in the University of 

 Dublin, and Royal Astronomer of Ireland, 

 [Continued from p. 137.] 

 [17.] '^T^HE following remarks may be useful, as serving to 

 A illustrate and develope the general analysis con- 



