On some Extensions of Quaternions. 125 



The watery solutions of these iodides are not precipitated by 

 ammonia^ and only become turbid with a great excess of potash. 

 The precipitate thus obtained dissolves in boiling water^ and the 

 solution gives crystals identical with the first ; in fact^ the iodide 

 is not decomposed by the potash, but it is insoluble in a solution 

 of that alkali. With oxide of silver, the solutions of these iodides 

 furnish iodide of silver, and the solution retains a very energetic 

 base; it rapidly absorbs carbonic acid from the air, aild fur- 

 nishes therewith crystals possessing an alkaline reaction. This 

 base, to whigh I give the name of sethylo-quinine, may be ob- 

 tained by evaporating the solution in vacuo, when it forms an 

 amorphous mass ; it dissolves in alcohol, and is precipitated from 

 this solution by aether in colourless crystals. It is decomposed 

 even at a temperature of 348° F. With this base I have pre- 

 pared the following salts : — 

 Neutral sulphate of gethylo- "\ ^44 -rrsg m2 r\b ana 



quinine J 



Acidsulphateof^thylo-quinine C^^H^^N^O^SO^ + HO.SO^. 



Chloride of ^thylo-quinine . C^^IP^N^O^ . CI. 



Platinum double salt . . . C44H29N2 04.Cl+HCl+2PtCP. 



All the properties of these compounds show that sethylo-qui- 

 nine belongs to the fourth class of Hofmann's bases ; it is a base 

 corresponding with oxide of ammonium, NH'*0. Quinine is 

 therefore a nitride base (of the third class), and contains in the 

 molecule C*^ H^"^ N^ 0"^ three compound radicals. There is no 

 doubt after this that the molecule and equivalent of quinine must 

 be expressed by the formula C^^ H^"* N^ O'*. As to the com- 

 pound radicals which enter into the composition of quinine, I 

 should lose sight of the region of facts if I attempted to pro- 

 nounce an opinion upon them. 



XIX. On some Extensions of Quaternions. By Sir William 

 Rowan Hamilton, LL.D., M.B.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 vol. vii. p. 499.] 

 [7.] T ET us now consider generally the associative law of 

 J--^ multiplication, which may be expressed by the for- 

 mula already mentioned but reserved in [I.], 



L.L'o" = Lt'.c"; (51) 



or by this other equation, 



h'''/^ff = l'e^/'^g' (52) 



