464 Prof. Williamson on Chemical Nomenclature. 



that is, 



M 2 + 4«/37=0, 



or, what is the same thing, 



(«+/3+Y + l) 2 + 4«/37=0; 

 and from the symmetry of this equation we see that when it is 

 satisfied 



the lines OB', OC f , Oct will lie in a plane, 



„ OC, OA', 0/3 „ „ 



„ OA', OB', 7 „ „ 



viz. this will be the case when the point is situate in the cubic 

 surface represented by the last-mentioned equation ; this com- 

 pletes the demonstration of the solid theorems. 



It is clear that considering five points 1, 2, 3,, 4, 5 in a 

 plane, then, since any one of these may be taken for the point 

 O' of the foregoing theorem, the theorem exhibited in the first 

 instance as a theorem relating to a triangle and two points, and 

 afterwards as a theorem relating to a quadrangle and a point, is 

 really a theorem relating to five points in a plane. There are, of 

 course, five different systems of points (P, Q, R, S), correspond- 

 ing to the different combinations of four out of the five points. 



Cambridge, March 6, 1865, 



LXIII. On Chemical Nomenclature. 

 By Alexander W. Williamson, F.R.S., F.C.S.* 



I HAD some weeks ago the honour of submitting to the 

 consideration of the Chemical Society a few practical sug- 

 gestions on the subject of chemical nomenclature, framed in the 

 hope of diminishing the inconsistencies which prevail in it at 

 present, and of aiding the development of its best tendencies. 



My chief proposal was to adopt, as systematically as possible, 

 terms such as mercurous nitrate, Hg 2 (N0 3 ) 2 ; mercuric hydro- 

 nitrate, Hg HO NO 3 ; hydric sulphate, H 2 SO 4 ; potassic hydrate, 

 KHO; hydropotassic sulphate, HKSO 4 ; hydrodisodic phos- 

 phate, HNa 2 P0 4 ; sodic sulphate, Na 2 S0 4 ; sodic disulphate, 

 Na 2 S 2 O 7 , &c. ; ferric oxydisulphate, Fe 2 (SO 4 ) 2 ; ferric dioxy- 

 sulphate, Fe 2 O 2 SO 4 , &c. The result of two evenings' discussion 

 of the subject was to show that the principles of such nomencla- 

 ture are, upon the whole, approved, and the names formed in accord- 

 ance with those principles offer altogether greater proportional 

 recommendations than any other names which are before che- 

 mists. 



* Communicated by the Author. 



