A distinet cleavability was not observed. 
The erystals deposited from acetone, which were very large but 
dull, show a predominance of a over 4; they are much elongated 
along the vertical axis and further possess a form which is probably 
{233} with (233) : (100) = 67°33’, calculated 67°24’. On a there is 
diagonal extinction; the optical axial plane is {010}. One optical axis 
descends almost perpendicularly on a. 
The specific gravity is 1,603, at 17°, the equivalent volume 119,77. 
Topical axes: 7: wy: w = 5,0596 : 7,5561 : 3,1350. 
Although the parameter-relation a: and the angle 8 in this isomer 
are comparable with those of the 1-2-3-derivative : 
1-3- Dichloro-2-Nitro- Benzene: a:b = 0,6696:1; 8 = 87° 52’ 
1-2- Dichloro-3-Nitro-Benzene: a:b = 0,6472:1; @=90°. 
ent 
their crystalline forms are still rather different; the relation — of 
c 
the latter substance is about 1°/, that of the first derivative. 
ce. 1-3-Dichloro-5-Nitro- Benzene. 
C,H;.Cl.Cl.(NO,) ; melting point: 65° C. 
(l) 5 
In alcohol or glacial acetie acid, in which solvents the compound 
exhibits a remarkably great crystallisation power, there are generally 
formed very long, flat columns of considerable thickness, or also 
right-angled or obtusely truncated pale-sherry coloured small thin 
plates. Owing to the great softness of the substance and its great 
plasticity, the erystals are in most cases so ill-formed and distorted 
that measurements become impossible. With very slow evaporation we 
sometimes get better formed crystals although they are very poor in 
planes. They have a peculiar odour resembling nitrobenzene. 
Monoclino-prismatic. 
a:6=0,5940:1 ; B= 58? 43’. 
Forms observed: « = {100}, broad and very lustrous; 5 = {010}, 
narrower and less lustrous; it is often absent altogether; m — {110}, 
narrow and c= {O01}, small but very reflecting; the habitus is 
elongated along the c-axis and then flattened {100}. 
Measured: Calculated: 
beam (OLO GLO) * 63.5 
GG (100) (O01) =" 58543 == 
a:m= (100): 110) = 2658 26°55! 
m:m = (110): (110) = 126 15 126 10 
me = (410), (OO  — 62 25 
GOS 
h:¢ =(010):(001) = 8957 90 0 
