( 439 ) 



the 6*-cixis, witli lladeiiiiiu' uloiiii l\Nf> |);irall('l pUiiies of )» \ perfectly 

 cleavabic towards JOOlj. 



The following angles were nioasiired : 



Measuri'd: Cdlcuhiled : 

 C : ill = (OOl ) : (1 10) = * 84" 57/ — 



C:q=z (001) : (Oil) = - 35° 51' — 



in : /// = (110) : (110) =r * 83° 3' — 



,» : q = (110) : (Oil) = 61^ 557/ ^^^'' ^^'/Z 



/// : q = (110) : (Oil) = 72° 18' 72" 15' 



7^/ : n =z (110) : (100) = 41° 34' 41° 317/ 



On |001j not observable l)iit on S110| vci-y distinctly diciiroïc ; 

 foi' vibrations parallel to the r-axis, grass-green ; ajid yellowish-green 

 for vibrations perpendicular thereon. The angle of extinction is very 

 difficult to determine; it amounts to about 12" in regard to the c-axis 

 on the planes of jllOj. 



The optical axial [)lane is *010| : on }001J one axis is visible at a 

 small angle with ilie normal to that plane; the inclined dispersion 

 is extraordinarilv stroui»' : i) <^ v. 



The sp. gr. of the crystals is 1.351 at 15°, the equivalent volume 

 is 121.39. 



Topic parameters : / : if' : <'^ — 5.1206 : 5.7277 : 4.1784. 



4. A small addition of the Jiitroso-compound to the nitro-com|>ound 

 causes a |)erceptible depression of tlie melting i)oint of the latter sub- 

 stance. As, therefore, no certainty is obtained as to the formation of 

 mixed crystals of these closely related derixatives — for a melting curve 

 with an al)S()lute minimum might be also present — a few preliminary 

 quantitative experiments were carried out, Avhich showed that we have 

 here indeed an ordinaiy binary meltingpoijitline with eutecticum. 

 It was fui-lher sho^vn l»y more detailed microscopic tests that from 

 mixed fusions of the two compounds is always deposited a niivtwe 

 of the iii'lloic uitroaceto-anilide crystals and the (jrccn nitrosoaceto-anilide 

 crystals with a totally dilfereiit aspect. At the side of the nitroso- 

 compound a perceptible (piantity of the nitro-derivative is carried 

 down by the deposited crystals as solid solution ; at the side of the 

 nitro-derivati\e a formation of solid solutions conld not be ascertained 

 in this way. In any case, if there should be a slight mixing, it is 

 limited on the side of ihc nitroso-compound to a few percent of the 

 nitro-com|)()un<l ; the hiatus is therefore enormously extended. 



Finally l)e it observed here that l)oth substances ai-e very volatile ; 

 the vapoui- of the nilroso-conqjound is ijeUoivlsli (jreeii. 



