— 156 — 



Oxygen in ethyl enic bond . O^ 1,643 



Oxygen in hydroxylic bond . O 1,525 



Chlorine CI 5,967 



Bromine Br 8,865 



Iodine . . , . I 13,900 



Ethylene linking / = 1,733 



Acetylene linking ..../= 2,398 



We abstract the following data which are of interest to our readers, 

 from a paper by C. Blass 1 ) on the crystallographic-optical properties of 

 organic compounds: — 



Patchouly alcohol, Ci 5 H 26 0. Hexagonal, a : c = 1 : 0,56528. Moderate 

 negative double refraction. (The figures given by Traube, which differ from 

 the above, may refer to another alcohol.) 



Cedrol, Ci 5 H 26 0. Optically active, laevorotatory. Rhombic, a:b:c 

 = 0,98385 : 1 : 0,70502. Hardness about 2. Cleaves excellently towards 

 {OOlJ, less clearly towards {l 10 j. Positive double refraction. 



Cypress- camphor, Ci 5 H 3 6 0. Differs plainly from cedar- camphor. 

 Rhombic, a : b : c = 0,98844 : 1 : 0,71772. Cleavage same as for cedrol. 



Guajol, C15H26O. Trigonal-pyramidal, a : c = 1 : 0,54959. Perfect pris- 

 matic cleavage. Hardness about 4. Very faint positive double refraction. 



Benzoyl eugenol, CnHi 6 3 . Monoclinic, a : b : c = 1,5829 : 1 : 1,0713, 

 fi = 80° 23' 30". Most perfect cleavage towards {00l}, less clearly to- 

 wards {llO}. Hardness about 4. 



Acetisoeugenol , Ci 2 Hi 4 3 . Rhombic, a : b : c = 0,68815 : 1 : 0,97672. 

 Cleavage towards (oiol. Hardness about 5. Fairly strong double refraction. 



Isoapiol (teapiol), Ci 2 H 14 4 . Monoclinic, 0,876502:1 : 1,7878, /? = 89° 10\ 

 Thin tables. Perfect cleavage towards {00l}, less clearly towards {no}. 

 Hardness about 1. 



Menthylbenzoate, Ce^COOCioH^. Rhombic, a : b : c = 0,76134 : 1 

 : 0,24476. Most perfect cleavage towards {00l}, less clear towards {oio}. 



Guajol-glycerol , Ci 5 H 2 60(OH) 2 . Rhombic, a: b = 0,23916 : 1 cleavage 

 towards {llO}. 



W. Richarz 2 ) has crystallographically examined ia series of aromatic 

 compounds, and in particular cinnamic acid and its halogen derivatives. 

 It is well-known that cinnamic acids of different origin differ in their pro- 

 perties, a subject which has been closely investigated by Erlenmeyer 3 ), 

 above all others. The material used by Richarz, in fact, was supplied by 



x ) Krystallographisch-optische Untersuchungen organischer Verbindungen, Inaug.-Dissert., 

 Breslau, 1910. See also Chem. Zentralbl. 1910, II. 871. 



2 ) Krystallographisch-optische Untersuchungen aromatischer Verbindungen, insbesondere 

 der Zimtsaure und ihrer Halogenderivate. Inaug. Dissert. Breslau 1911. 



s ) Comp. Report April 1909, 140; October 1909, 211; April 1910, 189; October 1910, 203. 



