( 509 ) 



Pi={ c—d,—a, O - g, h) Q\={ d, c, 0,-^n, -h,—g) 



P2 = {d, c, 0,—a, h, //) Q2 = {c,—d,—a, O, g—h) 



P3 = (0,— ƒ, g—h—a, 0) ^3=:(/, O, h, g, O—a) 



P4. = {f, 0,~h,—g, 0,—n) Q4: = {0,—f—g, h—a, 0) 



Fb = {g,~h, O, ƒ, c—d) Q4. = [h, g—f, O, d, c) 



FQ^ih, g, f, 0—d—c) Q6 = {g,-h, 0,—f—c, d), 

 if besides is satisfied 



ch -\- dg =: a f — gh = 0. 



Tlie peculiarity appearing with this example taken for simplicity's 

 sake, that the right lines show mutually some incidences, is lost by 

 submitting the coordinates in Sp^ lirst to a linear transformation. 



In the same way, indeed, we can formulate for all Cff. indicated 

 in spaces of a lower number of dimensions an analytical definition 

 by deducing the coordinates of their elements from those of the 

 elements of K^^^. 



Chemistry. — ''On the co?istitutlo?i of V A's Gev^ss's o.vy}nethyldinitro- 

 beiizonitrile" . By Dr. J. J. Blanksma. (Communicated by Prof. 

 A. F. Hollkman). 



By the action of potassiumcyanide on mela-dinitrobenzene 

 in methylalcoholic or ethylalcoholic solution , Lobry dk Bruyn ^) 

 obtained in 1882 the oxymethyl- or oxyethylnitrobenzonitrile 

 C«H3 (OCH3) CN NO, 1. 2. 3. 



The investigation of these substances was continued afterwards by 

 Van Geuns ^) who succeeded in saponifying these nitriles to acid- 

 amines and in preparing the corresponding acids thereof. At the 

 same time Van Geuns showed that in both substances a further 

 nitro-group can be introduced by nitration with nitric and sulphuric 

 acids thus yielding the compounds CgH,(OCHs) CN (NO,), m.p. 113° 

 and CeH,(0C,H5) CN (NO,), m.p. 63°, These two compounds contain 

 a movable nitro-group which may be readily replaced by OH, 

 OCH3, NH„ NHCH3, NHC.H, etc. ^ 



As, however, the place where the nitro-gi'oup had been introduced 

 had remained unknown, the constitution of these derivatives was 

 consequently also unknown. 



When Van Geuns, owing to his departure for India was obliged 



1) Recueil 2, 205. 



2) Dissertation Amsterdam 1903. 



